Seiko 6R35 Repair: The Seiko SPB147J1 is a faithful re-interpretation of the legendary 62MAS, Seiko’s first professional dive watch from 1965. While it retains vintage aesthetics, it benefits from modern materials and an upgraded movement, the Calibre 6R35, offering an impressive 70-hour power reserve and hacking functionality.
This particular Seiko 6R35 Repair arrived at our workshop completely stopped. The owner had attempted to regulate the watch but unfortunately slipped, damaging the balance wheel. To diagnose the issue, we installed a balance assembly we had on hand, which got the movement running, but with low amplitude. Given this, we ordered a new balance wheel and proceeded with a full service of the movement and case to restore the watch to peak performance.
Understanding the Seiko 6R35 Movement
The Calibre 6R35 is a modern automatic movement based on the 6R15, featuring:
- 70-hour power reserve, providing nearly three days of runtime
- Hand-winding and hacking, allowing precise time-setting
- Diashock protection, improving shock resistance
While durable, incorrect handling—such as a misstep during regulation—can cause balance or hairspring damage, requiring servicing to restore function.
Seiko 6R35 Repair: Diagnosing the Issue
Upon disassembly, we confirmed that the balance wheel was damaged, preventing proper operation. To test the movement, we installed a spare balance assembly we had on hand. While this got the watch running again, the amplitude remained too low, indicating that a new balance wheel was required.
Additionally, the movement showed signs of dried lubrication and dirt buildup, which could further impact performance. Given these findings, a full overhaul was necessary.
The Service Process – Seiko 6R35 Repair
Disassembly and Cleaning
The 6R35 movement was fully dismantled, with each part carefully inspected for wear. The jewels, gear train, and escapement were manually cleaned to remove old oils and debris.
Next, the components underwent multi-stage ultrasonic cleaning, ensuring all contaminants were eliminated before reassembly.
Installation of a New Balance Wheel
Once the ordered new balance wheel arrived, it was carefully installed to replace the damaged component. This ensured the movement could achieve the correct amplitude and beat error for precise timekeeping.
Reassembly and Lubrication
With the movement now cleaned, fresh lubricants were applied at key friction points to ensure smooth operation and longevity. The new balance wheel was installed and tested, confirming a significant improvement in amplitude.
Regulation and Calibration
Once reassembled, the watch was regulated in multiple positions to meet Seiko’s accuracy standards. Adjusting the beat error further optimised the movement, enhancing overall stability.
Final Testing and Case Restoration
After servicing, the watch underwent multi-day testing to ensure accuracy and power reserve. With the new balance wheel installed, amplitude was restored, and timekeeping performance was significantly improved.
The case was then cleaned and pressure tested to verify its water resistance, ensuring it was ready for everyday use.
Seiko 6R35 Repair: Restoring a Modern Dive Classic
The Seiko SPB147J1 is a stunning modern tribute to the 62MAS, combining heritage with cutting-edge movement technology. Thanks to a new balance wheel and a full Seiko 6R35 repair, this watch is now running at peak performance, ready for years of reliable service.
If your Seiko 6R35 movement requires servicing or repair, get in touch with us. Follow us on Facebook for more updates on our latest watch restorations.
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