Most watch owners know, in a general sense, that automatic watches need to be serviced periodically. They've seen the recommendation — every five to seven years, typically — and they've filed it away as something to deal with eventually. But very few people understand what's actually happening inside their movement between services, why lubrication matters so much, and what the consequences of skipping a service actually look like in practice.
This guide covers all of it. What lubricating oils do inside a movement. How they degrade over time and why that degradation is inevitable. What happens to a movement that goes too long without service — the sequence of events that turns a perfectly good automatic into an expensive repair. What a professional service actually involves, step by step. And how to recognize the signs that your NH35, NH34, NH72, or any other movement in the Watches By Cody collection is telling you it needs attention.
Understanding this doesn't require a watchmaking background. It requires only the willingness to understand the thing you're wearing on your wrist — and that understanding, once you have it, makes you a significantly better watch owner.
Part One: What Lubricating Oils Do Inside a Movement
The Friction Problem
A mechanical watch movement is a precision machine operating at extraordinarily small scales. The NH35, for example, beats at 21,600 vibrations per hour — 6 beats per second, every second, every hour, every day the watch is worn. The escapement — the component responsible for releasing the energy of the mainspring in controlled increments — engages and disengages 21,600 times per hour. The gear train transmits energy through a series of wheels and pinions rotating at different speeds. The balance wheel oscillates continuously, pivoting in jeweled bearings with clearances measured in microns.
At these scales and these frequencies, friction is an existential threat. Metal surfaces in contact under load, moving against each other at high frequency, generate heat and wear. Without intervention, the metal would wear rapidly — pivots would widen their jewel holes, gear teeth would wear flat, the escapement would become imprecise, and the watch would stop running within months.
Lubricating oils solve this problem by interposing a molecular layer between metal surfaces — a layer thin enough not to interfere with the precision of the mechanism but thick enough to prevent metal-to-metal contact. The oil film supports the load, reduces friction dramatically, and allows the movement to operate at the precision and frequency it was designed for without destructive wear.
The Different Oils and Where They Go
A professional watch service doesn't use a single oil. It uses multiple different lubricants — each formulated for the specific conditions of the part being lubricated. This is one of the things that distinguishes a professional service from a DIY attempt: the knowledge of which lubricant goes where, in what quantity, and why.
Mainspring grease. The mainspring — the coiled spring that stores energy when wound and releases it to drive the watch — is lubricated with a grease rather than an oil. The mainspring operates under high load and relatively slow speed, which requires a lubricant that stays in place under pressure rather than flowing away. Mainspring grease is specifically formulated to remain viscous under the compressive loads the spring generates.
Gear train oils. The gear train — the series of wheels and pinions that transmit energy from the mainspring to the escapement — operates at moderate speeds and loads. It uses a thin oil applied to the pivot points (where the staff of each wheel rotates in its jewel bearing). The oil must be thin enough to flow into the clearance between pivot and jewel but viscous enough to stay there during operation.
Escapement oils. The escapement — the most critical and most precisely manufactured component in any watch movement — uses the most specialized lubricants. The pallet fork and escape wheel engage with each other 21,600 times per hour, creating impact loads on the surfaces at extremely high frequency. The oil used here must be extremely thin (to not interfere with the geometry of the engagement) and extremely stable (to resist degradation under the repeated mechanical impacts). Escapement oils are among the most expensive and precisely specified lubricants in watchmaking.
Keyless works lubricants. The crown and its associated mechanism — the keyless works — receive a grease rather than an oil. This is the mechanism you engage when you pull the crown to set the time. It operates infrequently but under significant manual load, requiring a lubricant that stays in place and doesn't migrate to other components.
Balance staff pivot oils. The balance staff — the axle on which the balance wheel rotates — pivots in jeweled bearings at the movement's beat rate. These bearings receive a tiny drop of oil precisely placed on each pivot. The quantity is critical: too little and the friction is insufficient reduced; too much and the oil migrates onto the balance wheel or hairspring, disrupting timekeeping.
Click spring and ratchet lubricants. The winding mechanism — the click, click spring, and ratchet wheel that allow the crown to wind the mainspring in one direction — receives a specific grease to reduce wear on the ratchet teeth and click mechanism.
The Quantity Problem
One of the most counterintuitive aspects of watch lubrication is that more is not better. The quantities involved in a professional watch service are extraordinarily small — measured in fractions of a milliliter, applied with tools that deposit single drops no larger than a fraction of a millimeter in diameter.
An excess of lubricant is as problematic as a deficiency. Oil that migrates from its intended location can contaminate the hairspring — the tiny spiral spring that controls the balance wheel's oscillation rate — causing it to stick to adjacent coils and affecting timekeeping dramatically. Oil on the dial side of the movement can cause dial staining. Oil on the pallet jewels can thicken in cold temperatures and cause the escapement to lock up.
Professional watchmakers learn oil application through years of training and practice. The tools used — Rodico (a specialized putty for picking up and placing tiny components), oilers with precisely calibrated tip diameters, and timing machines to verify the results — are themselves precision instruments. 
Part Two: How Lubricants Degrade Over Time
This is the section that explains why service intervals exist — and why they're not arbitrary.
Evaporation
The thinnest oils used in watch movements — particularly escapement oils — are volatile enough to evaporate slowly over time. At room temperature, the rate of evaporation is slow enough to be imperceptible in the short term. Over years, however, the oil film thins as molecules escape into the atmosphere, gradually reducing the lubricant's effectiveness. In the escapement specifically, where the oil film is extremely thin to begin with, evaporation can reduce it to nothing within five to ten years.
The rate of evaporation is affected by temperature. Watches worn in warm climates or stored in warm environments will see faster lubricant evaporation than those kept in cool conditions. This is one of the reasons service intervals are given as ranges rather than fixed periods — five years in a temperate climate may be equivalent to three years in a hot one.
Oxidation
Watch oils oxidize when exposed to oxygen — the same chemical process that causes metal to rust and cooking oil to go rancid. Oxidation changes the molecular structure of the lubricant, typically causing it to thicken and darken. Oxidized oil is less effective at reducing friction and, in advanced stages, can become a contaminant rather than a lubricant — gumming up the components it was supposed to protect.
The rate of oxidation depends on the oil formulation, the temperature, and the degree of mechanical agitation the oil experiences in use. Modern synthetic watch oils oxidize significantly more slowly than the natural oils used in watches through most of the twentieth century — which is one reason service intervals have extended from three years to five to seven years as synthetic lubricants have replaced earlier formulations.
Separation and Migration
Some lubricants — particularly greases — can separate over time into their constituent components. The base oil and the thickening agent that gives the grease its viscosity can separate, leaving a thinner oil that migrates away from the intended location and a dried residue that provides no lubrication at all.
Migration is a related problem: lubricants can move from their intended location through capillary action, gravity, or centrifugal effects during the movement's operation. Oil that was precisely placed on a pivot can migrate along the pivot staff toward the balance wheel. Grease in the keyless works can migrate to adjacent components. Every migration event both depletes the lubrication where it was intended and contaminates the component it migrated to.
Contamination
Even in a sealed watch case, the lubricants inside a movement are not isolated from contamination. Dust particles too small to be visible to the naked eye can enter through the crown tube, accumulating in the oil deposits over time. These particles act as abrasives, accelerating wear on the metal surfaces the oil was supposed to protect.
Metal particles generated by wear — even the microscopic wear that occurs in well-lubricated components — accumulate in the oil over time, further increasing its abrasive quality. This is a self-reinforcing process: wear generates particles, particles accelerate wear, accelerated wear generates more particles.
The Combined Effect: What Degraded Lubrication Does to a Movement
When lubricants have degraded — through evaporation, oxidation, separation, migration, or contamination — the effects on the movement are predictable and progressive.
Increased friction is the first consequence. The metal surfaces that were protected by an oil film now experience greater direct contact. The escapement, which requires the most precisely controlled friction of any component in the movement, is typically the first to show the effects — the watch begins running less consistently, with greater variation in its rate across different positions and temperatures.
Increased wear follows increased friction. Pivot holes in jewels — which should maintain a consistent clearance with the pivot they support throughout the watch's service life — begin to widen as the hardened metal staff wears against the unlubricated jewel. This widening increases the play in the pivot, reducing the precision of the gear train and affecting timekeeping accuracy.
Gumming occurs when oxidized or separated lubricants become viscous enough to impede the movement's operation. A gear train that is gummed — where the lubricant has become a sticky residue rather than a flowing film — requires significantly more energy to rotate. This increased resistance depletes the mainspring's power reserve faster and, in severe cases, can prevent the movement from running at all.
Magnetization and contamination compound the effects. A movement that has been running without adequate lubrication for years typically has both contaminated lubricants (with metal particles from the accelerated wear) and components that have developed slight magnetic properties from the friction-generated heat. Both conditions persist after the lubricants are simply replenished — they require the full disassembly and cleaning that a proper service provides.
Part Three: What Happens When a Movement Goes Too Long Without Service
The consequences of deferred servicing follow a predictable progression — from performance degradation to mechanical damage. Understanding this progression makes the case for timely servicing far more compelling than any arbitrary "five-year rule."
Years 1-3: Normal Performance
In the first years after a service, a well-lubricated movement performs as designed. The lubricants are fresh and properly placed. The components are clean. The timekeeping is consistent and accurate. There is nothing observable to suggest that anything is degrading — and nothing is, meaningfully, yet.
Years 3-5: Early Degradation
By the third to fifth year, lubricant degradation is underway but not yet critical. The thinnest oils — particularly escapement lubricants — have begun to thin through evaporation. Timekeeping may show slightly increased variation, particularly in the rate difference between dial-up and dial-down positions. The watch runs, keeps adequate time, and shows no obvious symptoms.
This is the period when servicing is most cost-effective. The components are still in good condition, requiring only cleaning and relubrication. The movement comes out of service performing as well as or better than when it went in, and the total cost of the service is minimized.
Years 5-8: Moderate Degradation
Between years five and eight, degradation becomes more significant. Escapement lubricants may be effectively depleted. Gear train oils have thickened from oxidation. The movement is running with meaningfully increased friction in some or all of its gear contacts. Timekeeping accuracy degrades noticeably — what was ±5 seconds per day after the last service may now be ±15-20 seconds per day or more. Position variation increases significantly.
Servicing at this point is still straightforward but requires more careful attention to component inspection. Some pivot jewels may show early signs of wear that need to be noted. The service cost is higher than an early service but still reasonable.
Years 8-12: Advanced Degradation
By years eight to twelve without service, the movement is in advanced degradation. Lubricants are severely depleted or oxidized. Metal wear on pivots and jewels is measurable. The mainspring may show fatigue from years of operation without the proper grease. Timekeeping is significantly affected — the watch may be losing or gaining 30+ seconds per day or stopping unexpectedly.
Servicing at this point requires careful evaluation of components. Worn pivot jewels may need to be staked or replaced. The mainspring may need replacement. The gear train may show wear patterns that require attention beyond simple cleaning and relubrication. Service cost increases substantially.
Beyond 12 Years: Damage Mode
A movement that has gone 12 or more years without service is likely in damage mode — where the degraded lubrication has caused physical changes to components that cleaning and relubrication alone cannot address. Widened pivot holes, worn gear teeth, a fatigued mainspring, and corrosion from contaminated lubricants may all require parts replacement.
At this stage, the cost of a full restoration service can exceed the replacement cost of the movement itself — particularly for affordable calibers like the NH35 where a new movement is relatively inexpensive. The practical decision at this stage is often between a full parts-replacement restoration and movement replacement.
The important point is that this outcome is entirely preventable. A movement serviced on schedule never reaches this stage — the components are maintained in good condition, and the service cost remains predictable and reasonable throughout the watch's life.
Part Four: What a Professional Service Actually Involves
Most watch owners have no idea what happens during a professional watch service. This is understandable — the work happens behind closed doors, often takes days or weeks, and returns the watch looking identical to when it went in. Understanding what a watchmaker actually does during a service changes how you think about the cost and the interval.
Step 1: Timing and Condition Assessment
Before disassembly, the watchmaker records the movement's current performance — rate in multiple positions (typically dial up, dial down, crown up, crown down, crown left, crown right), amplitude, and beat error — using a timing machine. This baseline documents the movement's condition before service and provides a target for post-service performance.
The watchmaker also examines the movement for any existing damage, unusual wear patterns, or component failures that will need to be addressed during the service. Parts that need replacement are identified before disassembly begins.
Step 2: Case Disassembly
The movement is removed from the case. The caseback, crystal, bezel, and crown are removed and inspected. Gaskets — the rubber seals that provide water resistance — are examined for condition and set aside for replacement. The case itself is cleaned using appropriate methods (ultrasonic cleaning for metal components, careful manual cleaning for components that ultrasonic cleaning could damage).
Step 3: Movement Disassembly
The movement is disassembled into its component parts. For an NH35, this means separating the movement into hundreds of individual components — wheels, pinions, jewels, the escapement, the balance assembly, the keyless works, the winding mechanism, and the mainspring.
Disassembly follows a specific sequence that varies by movement family and is learned through training. Components are laid out in organized fashion — either on a movement holder or on a parts tray — in the sequence of disassembly, so reassembly proceeds in the correct reverse order.
The balance assembly — the most delicate component in the movement, with the hairspring that controls timekeeping — is removed and handled with exceptional care. The hairspring is a spiral of metal wire measured in microns of thickness. Any contact with tools, any deflection, any contamination, changes its mechanical properties and affects timekeeping.
Step 4: Cleaning
Every component is cleaned to remove all traces of old lubricant, contamination, and wear debris. Professional watch cleaning uses a multi-stage ultrasonic cleaning process — the components are subjected to ultrasonic vibration in a series of cleaning solutions, each progressively cleaner, to dissolve and remove contamination.
The cleaning solution sequence typically involves a degreasing solvent (to remove oil-based contamination), a rinsing solution (to remove the degreaser), and a final rinse in clean solvent (to leave the components free of any cleaning residue). After the final rinse, components are dried — either in a heated chamber or by blowing clean dry air across them.
The balance assembly is cleaned separately and by hand — ultrasonic cleaning risks deflecting the hairspring or displacing the timing washers that balance the assembly.
Step 5: Inspection
With every component clean and dry, the watchmaker inspects each one under magnification for wear, damage, or defects. Pivot holes in jewels are examined for wear. Gear teeth are inspected for chipping or flattening. The mainspring is examined for fatigue, set, or corrosion. The escapement components — the pallet fork jewels and the escape wheel teeth — are examined for wear on their engaging surfaces.
Components that don't meet specification are replaced. For common calibers like the NH35, NH36, and NH34, replacement parts are widely available and cost-effective. For rarer calibers, parts may need to be sourced from specialist suppliers or fabricated.
Step 6: Lubrication and Reassembly
Reassembly is the reversal of disassembly, with lubrication applied at each appropriate point as components are reassembled. The sequence matters — some lubricants must be applied before the next component is installed, because the component being installed would block access afterward.
Lubrication is applied with precision oilers — tools with tips calibrated to deposit a specific volume of oil. The watchmaker uses the correct oil for each application point, applied in the correct quantity. This step is where the skill and experience of the watchmaker is most directly expressed — the quality of the lubrication determines the performance of the movement coming out of the service.
The balance assembly is reinstalled last — it's the most sensitive component to handle and benefits from being placed into an already-assembled movement rather than having components assembled around it.
Step 7: Timing and Adjustment
With the movement reassembled, the watchmaker runs it on the timing machine again. The rate, amplitude, and beat error are measured across multiple positions and compared to the pre-service baseline and the manufacturer's specification.
Adjustments are made as needed. The regulator lever — which controls the effective length of the hairspring and thus the beat rate — is adjusted to bring the rate within specification. Beat error — the difference between the tick and the tock — is adjusted by moving the impulse jewel or adjusting the beat adjustment mechanism if the movement has one.
For an NH35, a good service target is a rate within ±10 seconds per day across all positions, an amplitude above 250 degrees, and a beat error below 1.0 milliseconds. A skilled watchmaker should reliably achieve these targets on a clean, undamaged NH35.
Step 8: Case Reassembly and Pressure Testing
The serviced movement is reinstalled in the cleaned case. New gaskets are fitted at the caseback, crystal, and crown. The watch is reassembled completely and subjected to pressure testing to verify that the water resistance meets its specification.
The pressure test uses either water pressure or air pressure to verify the sealed case's integrity. Any leak is identified and the gasket at the leak point is replaced and retested until the watch meets its rated resistance.
Step 9: Final Quality Check and Documentation
The completed service watch is worn on a timing machine or a wrist simulator for a period — typically 24 hours — to verify that the timing established on the bench is maintained in real-world operation. Any deviation from the target is addressed before the watch is returned.
The watchmaker documents the work performed, the parts replaced, and the post-service performance. This documentation is provided with the watch and serves as a service record for future reference.
Part Five: How to Know When Your NH35 Needs Service
The NH35's service needs don't announce themselves dramatically — the movement degrades gradually, and many of the signs are subtle enough to be missed by an owner who isn't looking for them. Here are the indicators that your NH35 is telling you it needs attention.
Timing Accuracy Has Changed Noticeably
The most direct indicator of a movement that needs service is a meaningful change in its timekeeping accuracy over time. If your NH35 was running +5 seconds per day after its last service and is now running +20 seconds per day, the change is significant — it suggests that the escapement lubricants have degraded enough to affect the balance wheel's oscillation rate.
You don't need expensive equipment to monitor this. A smartphone with a dedicated watch timing app (many free options exist) can give you a reliable rate measurement over 24 hours. Compare the current rate to what you know from when the watch was new or last serviced. A drift of more than 15-20 seconds per day from the post-service baseline is a meaningful signal.
Increased Positional Variation
All automatic movements run at slightly different rates in different positions — dial up, dial down, crown up, and so on. This is normal. What's significant is when the variation between positions increases over time.
If your NH35 runs +5 seconds per day dial up but -10 seconds per day crown down, the 15-second spread between positions suggests that the lubricants are no longer providing consistent performance across different orientations. Fresh lubrication significantly reduces this positional variation — a well-serviced NH35 typically shows a spread of less than 10 seconds between its best and worst positions.
The Watch Stops Unexpectedly
An NH35 that stops while being worn normally — with a full wrist day of movement to keep it wound — has a problem. In a recently serviced movement with healthy lubricants, the automatic winding system keeps the mainspring charged throughout a normal day of wear. Unexpected stopping while worn suggests either that the winding mechanism is not engaging properly (a mechanical fault), that the power reserve is not being maintained (a mainspring or rotor issue), or that the movement is encountering resistance from degraded lubricants that the winding system can't overcome.
The Seconds Hand Doesn't Sweep Smoothly
The NH35's seconds hand should sweep continuously — 6 increments per second, so smooth that it appears to flow rather than step. If the sweep appears to stutter, skip, or hesitate, the escapement is not releasing energy consistently. This is almost always a lubrication issue in the escapement specifically — the most common early sign of escapement oil depletion.
The Watch Needs Full Manual Winding More Often Than It Should
If you're wearing your NH35 regularly and finding that it needs manual winding at the start of the day — because it ran out of power overnight — the automatic winding system may not be charging the mainspring efficiently. This can indicate a rotor bearing that needs lubrication, a worn or weak mainspring that isn't storing energy effectively, or a winding pawl that is engaging inconsistently.
The Crown Feels Different
If the crown feels stiffer to wind or to set than it did previously, the keyless works — the mechanism controlled by the crown — may be drying out. The keyless works are lubricated with grease that eventually dries, making the crown feel sticky, gritty, or significantly stiffer than normal. This is both a performance issue and a potential water resistance issue — dried keyless works can allow water ingress through the crown tube.
The Watch Has Been Running Continuously for 5+ Years
If your watch has been worn daily for five years or more without service, it needs attention regardless of whether any of the above symptoms are present. The lubricants are degrading on a timeline that doesn't wait for symptoms to appear. By the time symptoms are obvious, some damage has already occurred. Servicing at the five-year mark is preventive — it addresses lubricant degradation before it becomes component wear.
After Any Significant Impact or Water Ingress
If your watch has been subjected to a significant impact — dropped on a hard surface, knocked sharply against something solid — have it inspected even if it appears to be running normally. The impact can displace components at a level too fine to affect obvious function immediately but significant enough to cause accelerated wear. Similarly, any confirmed or suspected water ingress requires immediate service — water inside a movement causes corrosion on the steel components that progresses rapidly.
Part Six: NH35 vs NH34 vs NH72 vs Miyota 8285 — Service Interval Comparison
The movements in the Watches By Cody collection have broadly similar service requirements — all are modern automatic movements with similar lubricant specifications and comparable service intervals. But there are differences worth knowing.
NH35, NH36, NH38 — Standard Service Interval
The NH35 family movements — including the NH36 (day-date) and NH38 (no-date) — have the same architecture, the same lubricant specifications, and the same service interval recommendation: every 5-7 years under normal daily wear conditions.
These movements are among the most serviced automatics in the world — watchmakers globally are familiar with them, parts are universally available, and service costs are reasonable precisely because the volume of these calibers in circulation has created a large, competitive service market.
NH34 GMT — Standard Service Interval with GMT Complication Consideration
The NH34 shares the NH35's core architecture and has the same basic service interval. The additional GMT complication — the extra gear train and hand that drives the 24-hour indication — adds components that require lubrication and inspection during service, but doesn't significantly change the service interval or cost.
The GMT hand's additional gear train is worth noting: it runs continuously alongside the main gear train and is subject to the same lubricant degradation timeline. Service timing should be the same as the NH35 — 5-7 years.
NH72 — Skeleton Movement Considerations
The NH72's open architecture means that some of its components are more exposed to environmental contamination than those of closed-dial movements. Dust that would be blocked by a closed dial can settle on the movement's exposed surfaces. This doesn't change the service interval meaningfully, but it does mean that the NH72 benefits more than most movements from careful handling — avoiding dusty environments when the caseback is open, for example.
The decorated surfaces of the NH72 require care during cleaning — the finishing on the bridges and mainplate is more susceptible to damage from harsh cleaning agents than the unfinished interior components of a standard movement. A watchmaker experienced with skeleton movements will clean the NH72's decorative surfaces with appropriate care.
Miyota 8285 — Similar Interval, Slightly Different Architecture
The Miyota 8285 uses similar lubricant specifications to the NH family but has slightly different architecture in its day-date mechanism and its higher beat rate (28,800 vph vs 21,600 vph). The higher beat rate means the escapement engages more frequently per hour — 28,800 times vs 21,600 — which means the escapement lubricant is subjected to more mechanical impacts per unit time. This could theoretically accelerate escapement lubricant degradation slightly, suggesting the lower end of the service interval range (5 years rather than 7) is more appropriate for the 8285 under heavy use.
Part Seven: Finding the Right Watchmaker for Your Seiko Mod
Not all watchmakers are equally suited to servicing Seiko mod watches — and finding the right one makes a meaningful difference to the outcome of a service.
What to Look For
Experience with Seiko NH movements. The NH35 family is the most common automatic movement in the mod ecosystem, and most watchmakers with any volume of work will be familiar with it. Ask directly: how often do they service NH35 or similar Seiko movements? A watchmaker who services these regularly will be faster, more confident, and less likely to encounter difficulties with the specific architecture of the caliber.
Proper equipment. A professional service requires ultrasonic cleaning equipment, a timing machine (for pre- and post-service performance measurement), precision oilers, and the correct lubricants for the movement being serviced. Ask whether the watchmaker has these tools — a watchmaker working without a timing machine cannot verify the quality of their own service.
Transparency about parts. If a component needs replacement during service, the watchmaker should tell you specifically what needs replacing, why, and what it costs before proceeding. A watchmaker who replaces parts without informing you, or who can't explain what was replaced and why, is not operating with appropriate professionalism.
References and reputation. For a first service, ask for references from other customers or look for reviews specifically mentioning automatic watch service. The watch community is active online — forums and social media groups for Seiko mod enthusiasts often have recommendations for trusted watchmakers in various locations.
What to Avoid
The "quick service" offer. A proper movement service takes time — disassembly, cleaning, inspection, reassembly, adjustment, and testing across positions. A service that is completed in the same day the watch is dropped off is almost certainly not a full service. A genuinely thorough service typically takes several days to a week.
Servicing without timing. If a watchmaker doesn't offer pre- and post-service timing measurements, they cannot tell you whether the service improved the movement's performance. Timing measurements are the watchmaker's accountability — they're how you verify the service was done correctly.
Excessive parts replacement. A legitimate service for an NH35 in normal condition requires cleaning, lubrication, and gasket replacement. It should not require extensive parts replacement unless the movement has been severely neglected or physically damaged. A watchmaker who quotes significant parts replacement on a movement that was recently running adequately should provide a specific explanation of what failed and why.
The Cost of an NH35 Service
The cost of a professional NH35 service varies significantly by location, watchmaker, and the condition of the movement. As a general range:
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Basic service (clean, oil, regulate): $80–$150 in most Western markets
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Full service with pressure testing and gasket replacement: $120–$200
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Service with parts replacement: Above $200, depending on what needs replacing
These costs are significantly below the equivalent cost for Swiss movement servicing — the NH35's wide distribution and the large number of watchmakers familiar with it creates price competition that benefits owners. Compared to the cost of movement replacement or, worse, the cost of repairing damage caused by deferred service, a timely service is consistently the most economical option.
Part Eight: DIY Servicing — What's Possible and What Isn't
The Seiko mod community has a strong DIY culture, and NH35 servicing is within the capability of skilled hobbyists with the right tools and a willingness to learn. Understanding what's realistically achievable helps set appropriate expectations.
What a Skilled DIY Enthusiast Can Do
Basic regulation. Adjusting the regulator lever to change the daily rate is accessible to anyone with a steady hand and a timing app to measure the results. No disassembly is required — the regulator is typically accessible through the caseback.
Caseback gasket replacement. Replacing the caseback gasket is straightforward — remove the caseback, replace the O-ring with the correct size, and reinstall. This is often worth doing at home between professional services, particularly for watches worn in water.
Crystal replacement. Replacing a scratched or cracked sapphire crystal requires a crystal press with the appropriate dies, but is achievable for a motivated hobbyist. Incorrect technique can chip the new crystal or compromise the crystal seal.
Basic disassembly and reassembly. With patience, the right tools, and excellent resources (the NH35 is one of the most documented movements in the world for hobbyist servicing), a DIY enthusiast can disassemble and reassemble an NH35. The risks are significant — the hairspring is fragile and easily damaged, the oiling requires precision that's difficult without practice, and mistakes are easy to make — but the community resources available make it more achievable than for less common movements.
What Requires Professional Equipment
Ultrasonic cleaning. Home cleaning with solvents and soft brushes can remove visible contamination but cannot match the thoroughness of ultrasonic cleaning. A movement cleaned by hand alone will have residual contamination in oil passages and on component surfaces that ultrasonic cleaning would remove.
Professional lubrication. The correct lubricants — specific Moebius or Nye Lubricants products for specific application points — are commercially available but expensive for one-time use. More significantly, the precision application equipment (calibrated oilers, Rodico) and the knowledge of exactly where and how much to apply requires experience that is difficult to develop through occasional DIY servicing.
Pressure testing. Verifying water resistance after reassembly requires pressure testing equipment that is not cost-effective for home purchase. A movement reassembled at home without pressure testing cannot be assumed to meet its original water resistance specification.
Movement timing across positions. Consumer timing apps provide basic rate measurements but can't match the precision of professional timing equipment across multiple positions. Post-service adjustment to professional standards requires professional timing tools.
The DIY Recommendation
For owners who want to maintain their movements themselves, the most practical approach is a hybrid: perform the accessible tasks (regulation, caseback gasket replacement) at home, and send the watch to a professional for full disassembly and cleaning every 5-7 years. This minimizes professional service costs while maintaining the movement's performance between services.
The Bottom Line
A mechanical watch movement is a precision machine that requires specific care to maintain its performance over time. The lubricants that protect its components from friction and wear degrade inevitably — through evaporation, oxidation, contamination, and migration — and the consequences of leaving them to degrade without replacement progress from subtle performance loss to significant mechanical damage.
Understanding this doesn't require a watchmaking qualification. It requires only knowing that the service interval recommendation exists for a reason — that the five to seven years between services is the period across which the lubricants can be expected to maintain adequate performance before their degradation begins to cause damage rather than just inconvenience.
The NH35, NH34, NH36, NH38, NH72, and Miyota 8285 movements in the Watches By Cody collection are all well-supported by the global watchmaker community. Parts are available. Watchmakers familiar with these calibers are accessible everywhere. And the cost of a timely service is a fraction of the cost of repairing a movement that has been allowed to degrade to the point of component damage.
A watch that is serviced on schedule performs better, lasts longer, and costs less to maintain over its lifetime than one that is deferred until symptoms appear. That's the simple case for lubrication and servicing — and it applies to every automatic movement ever made, from the most complicated Swiss chronograph to the most reliable Seiko mod.
Choosing the right watch is ultimately about more than just specifications—it’s about finding a piece that fits seamlessly into your daily life. The best watches are the ones you don’t have to think twice about—reliable, versatile, and naturally aligned with your personal style.
At Watches By Cody, our goal is simple: to offer watches that combine timeless design, dependable performance, and real-world wearability—without the unnecessary markup often found in traditional luxury retail. We focus on pieces that look refined, feel right on the wrist, and hold up over time.
If you’re ready to find a watch that fits both your style and your lifestyle, explore our latest collection at Watches By Cody and discover the piece that works for you.
