Often overshadowed by the moonlight of the Speedmaster, the Seamaster chronograph was meant for the sporty gentleman. I bought this watch from it’s original owner and he told me he wanted something he could wear for rally racing, swimming and still look smart at dinner parties. The watch was worn for 20 years and then left in a drawer for the next 30. It’s running like a dog and the chronograph is not engaging.
Yuck the case back gasket has melted.. Well that confirms the story that it has not been used in a long time, but the movement looks excellent.
No wonder it is not keeping time. One of the hairspring coils is tangled in the regulator pins.
Dial has some marks, but overall looks very nice.
Dial and hands removed. Everything looks to be in excellent condition.
Here you can get a better view of the hairspring. It must have received a proper shock at one point.
Best way to tackle the issue was unscrewing the boot from the balance cock and then carefully lifting the balance cock out, freeing the coil from the regulator pin. It worked and the hairspring is completely undamaged.
Now that the balance issue is sorted, I can start taking the movement apart.
I start with the top chronograph layer.
Almost down to the base movement. Everything looking very nice.
It’s important not to forget the crown wheel underneath the train bridge.
Here you can see the gear train layout.
Lastly I take the hour recorder and setting/winding mechanism.
All the parts are put into the cleaning machine baskets for cleaning.
All the parts cleaned and ready to be put back together.
Clean mainspring in the barrel.
I see that the balance moves freely after fitting the balance jewels.
I have put the gear train, setting lever/winding mechanism back in place. However I can’t wind the movement before fitting the hour recorder bridge as it also holds the lower barrel arbor pivot.
I fit the lower hour recorder mechanism.
I can now see that the gear train moves freely.
I start putting the chronograph bits back together.
All back together and running like it should.
It’s not always straight forward.. After fitting the dial and hands I noticed I had one large screw remaining in my parts tub. That was the screw that prevents the setting lever from unscrewing too far when removing the setting lever. Second time I fitted the dial and hands the hour recorder was creeping.
Third time lucky and the dials and hands are back in place.