WS 22: Servicing a SEIKO 7005 including replacing the balance

As you can see I already assembled the movement. But trust me, this movement is really easy to reassemble, especially with the two short cuts I took (calendar mechanism and winding system). The two critical steps in my opinion when assembling the movement are that the gear train is moving freely after replacing the top plate (this is by the way not typical for this movement but for any assembly). The freely moving gear train can be simply tested by carefully moving the gear wheels or by pushing the barrel teeth with a peg wood or brass tweezers. This should start the movement immediately even the spring is only wound a couple of turns. Also when replacing the balance assembly you have to make sure the lever fork moves when you softly try to move the balance wheel. Rob gives more details about this assembly in his article. Besides that, the assembly is really straight forward and not difficult at all.

Now (out of the alcohol bath) you can clearly see that the old hairspring (I placed it into the spare parts box) has deformations. The close-up below proves that it was a good idea to get that spare balance spring earlier and to consequently use it in this repair.

Please click on the last picture to read on >>>