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Seiko watch movement, Part 4


Now that the disassembly of my Seiko 7S26 movement has truly reached a point of no return, it’s time to flip the movement over and start disassembling the automatic winding unit and the oscillator unit.

The rotor with oscillating weight. This is where the winding mechanism starts.

The rotor rotates on a ball bearing and is secured with a screw.

Removing the rotor reveals Seiko’s Magic Lever winding mechanism.

A close-up of the Magic Lever mechanism. It really is quite clever.

Magic Lever components. It looks like the pawl is a slightly different shape from older 7S26s.

Removing the second reduction wheel.

Releasing the ratchet allows the main spring to unwind.

Lifting the balance wheel assembly up to release it.

The balance wheel assembly.

Removing the pallet bridge.

Oscillator unit disassembled.

Removing the bridge.

Bridge assembly removed.

That completes the disassembly of the automatic winding and oscillator units. In Part 5 I’ll get my mitts on the going train of the movement. I’ll find out how the power from the mainspring is released in a controlled manner to make the watch keep time.


  1. Noticed that it has been a while since you last updated this site. Would love to read and see the progress.

  2. Hi, your blog makes very interesting reading, it’s well photographed and explained.
    Please continue with Pt 5 !!!!

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