WS 22: Servicing a SEIKO 7005 including replacing the balance

This picture shows the balance cock turned over and offers a nice view of the hairspring. The curvature of the hairspring is less beautiful though. I marked that "squashed" area with the orange arrow. Also please note the brass block of the regulator (right side) where the hairspring is threaded. At around 1 o'clock you see the spring stud and the little screw of the spring stud holder. Just as a side note: if you regulate watches, do not touch or change the position of the spring stud holder. The spring stud holder is responsible for an even "tick and tock". If the "tick" and "tock" are the same length, the watch is in isochronisms.
The jewel in the center of the balance wheel is the connection to the lever fork that stops and releases the escape wheel. The brass part with the moon shaped cutout is the roller.
My problem was how to disconnect the balance from the balance cock. I did not see a way on how to move the brass block of the regulator! Instead of wasting a lot of time or damaging parts, I gave my pride a kick and called Rob. Rob spelled out the URL of his article where a close-up of the turned brass block was visible. That was the trick! Simply turn the brass block on the regulator and loosen the screw of the spring stud holder and the balance wheel can be separated from the balance cock. Good I called, I would have never guessed that the brass block could be turned with a pair of tweezers. Turned 90 degrees to free the hairspring.

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