A Grand Seiko 8J55-0010 came into Ross Watch Repairs for a Mini Service. The stainless-steel case and bracelet had noticeable scratches and signs of everyday wear, but a cosmetic refresh was only one part of the work. When the watch was opened, we found that the caseback gasket was missing—an important issue for protecting the quartz movement against moisture.

We fitted a new premium battery, replaced the missing gasket, resealed the case and pressure tested the watch. The watch passed the pressure test carried out after reassembly. We also polished the stainless-steel case and bracelet to reduce visible scratches. The entire Mini Service was completed within two hours.

Before the Mini Service: Scratches on the Grand Seiko Case and Bracelet

This Grand Seiko features a light silver dial with the distinctive 12, 3, 6 and 9 numerals and the Grand Seiko signature beneath the hands. The watch arrived on its original-style stainless-steel bracelet, showing marks from regular use across the case, bezel, links and clasp.

The before photographs show why a carefully carried out polish can make such a difference to a well-worn watch. Even where the movement works correctly, surface scratching and accumulated wear can make a quality timepiece look tired.

Inside the Grand Seiko 8J55 Quartz Movement

The 8J55 is a Grand Seiko quartz calibre, not a mechanical automatic movement. The reference 8J55-0010 identifies the movement and case family. Unlike a mechanical watch that is powered by a mainspring, this movement relies on its battery for power.

Grand Seiko’s official battery information lists an approximate five-year battery life for the 8J55 with a fresh cell, although actual replacement needs depend on the individual watch and its conditions of use.

After removing the caseback, we examined the quartz movement and battery compartment. The workshop photograph shows the exposed movement before completion of the reseal work.

The Missing Gasket: Why a Battery Change Alone Was Not Enough

The important discovery was that the old caseback gasket was missing. A gasket is a sealing component that sits between the caseback and watch case, helping keep moisture and dust away from the movement. Without it, the watch cannot be relied upon to maintain its intended seal, even if it appears perfectly normal on the outside.

Rather than simply fitting a battery and closing the watch, we addressed that missing protection as part of the Mini Service. The work included:

• Fitting a new premium-quality battery to the Grand Seiko quartz movement.
• Replacing the missing caseback gasket and resealing the watch.
• Carrying out a pressure test after reassembly, which the watch passed.
• Polishing suitable areas of the stainless-steel case and bracelet to reduce everyday scratches.
• Checking the watch after the agreed service work.

A passing pressure test is a useful result, but it applies to the test conditions used on the day. We are not claiming a particular depth or bar rating for this repair because the test setting has not been provided for this case study. A watch’s future resistance also depends on the continuing condition of its crown, glass, seals and case.

Grand Seiko’s official water-resistance guidance explains why the markings and condition of an individual watch matter when determining suitable water exposure.

Polishing the Stainless-Steel Bracelet and Case

Once the essential battery and sealing work had been carried out, the watch received a cosmetic polish. The aim was to remove or minimise many of the visible scratches on the bracelet, clasp and suitable exterior case surfaces, while respecting the watch’s original shape and finish.

The after photographs show the improvement: the bracelet has a cleaner, brighter appearance, the clasp looks tidier and the case has regained much of its sheen. As with any watch polish, deep dents or scratches cannot always be removed without taking away excessive material, so a careful approach is important.

Before and After: The Grand Seiko Mini Service Result

The final result was a refreshed Grand Seiko 8J55-0010 with a new premium battery, a newly fitted caseback gasket, a passing pressure test and a polished exterior. Crucially, this job did not require a quartz movement replacement or full movement overhaul.

From booking in to completion, this particular Mini Service took approximately two hours, helped by having the required battery and suitable sealing materials available. Other jobs may take longer depending on the watch’s condition and required parts.

Grand Seiko Battery Replacement and Mini Servicing in London

If your Grand Seiko needs a battery replacement, reseal, pressure test, bracelet clean or cosmetic polishing, Ross Watch Repairs can examine the watch and recommend the appropriate work. We offer free assessments and payment is taken on completion. No appointment is normally needed for visits to our branches.

See our Grand Seiko watch repairs, battery replacement and reseal and Mini Service information.

London Bridge / The Shard: Ross Watch Repairs, Unit 6, London Bridge Station, London SE1 9SG.

Canary Wharf: Ross Watch Repairs, Unit 4B, Cabot Place Shopping Centre, Canary Wharf, London E14 4QT.

For our UK postal watch repairs, send the watch to our Canary Wharf address by Royal Mail Special Delivery with suitable insurance cover. Please include your name, phone number, email, return address and a written note describing the fault or requested work inside the parcel. A £15 postal charge applies to postal repairs under £50, and return postage and packaging is normally around £10.

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