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The SEIKO (SII) NH35/NH36/NH37/NH38/NH39 Balance Stop Lever (#0601183) is a genuine Japanese-made component for the popular NH series automatic movements . This lever is the critical part responsible for the hacking (seconds stop) function – when the crown is pulled to the time-setting position, the balance stop lever engages the balance wheel to halt its oscillation, allowing precise time synchronization . This brand new original part is essential for watchmakers restoring proper hacking function when the original lever becomes worn or damaged.
Genuine Seiko/SII part – authentic Japanese-made component for NH35, NH36, NH37, NH38, and NH39 movements
Hacking mechanism component – engages the balance wheel to stop the seconds hand for precise time-setting
NH family compatibility – compatible across the most popular NH series calibers
Direct replacement – drop-in replacement for worn or damaged balance stop levers
Part Number: 0601183
Compatible Movements: Seiko NH35, NH36, NH37, NH38, NH39 (also known as 4R35/36/37/38/39)
Movement Family: NH Series (Basic Mechanical Series)
Function: Balance stop lever (hacking / stop-second device)
Hacking: Yes (seconds hand stops when crown pulled to position 2)
Movement Frequency: 21,600 vph (3 Hz)
Jewels: 24
Power Reserve: ~41 hours
Origin: Japan
Service and overhaul – replacing worn or damaged balance stop levers in NH series movements
Hacking function restoration – resolving issues where the seconds hand fails to stop when setting the time
Suitable for professional watchmakers and experienced repair technicians
1. Is this a genuine Seiko/SII part?
Yes, this is a genuine Seiko (SII/TMI) factory part made in Japan. The NH series is manufactured by Seiko Instruments Inc. (SII) and distributed by Time Module Inc. (TMI) . Using genuine parts ensures proper fit and maintains the movement’s factory functionality.
2. What is the function of the balance stop lever?
The balance stop lever is the component responsible for the hacking (stop-second) function. When the crown is pulled to position 2, this lever engages the balance wheel to stop its oscillation, thereby halting the seconds hand for precise time synchronization . This feature is one of the key upgrades of the NH series over older non-hacking movements like the 7S26 .
3. Which movements is this balance stop lever compatible with?
This balance stop lever is compatible with Seiko NH35, NH36, NH37, NH38, and NH39 movements . These are all based on the same NH35 architecture, with differences in complications (date/day-date/24-hour/open heart). The hacking function operates identically across all these calibers.
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