I used my 69 Speedmaster moonwatch today and everything worked well until I pressed the chrono button and after a few seconds running the watched stopped. I reset the chrono to zero, started it again and after a few seconds after the watch stopped running. I reset it to zero again and did not operate the chrono function. The watch worked well and keeps good time. What could be wrong with the chronograph function?

 

It needs a good service, the old oil changes to hard gum when old and mixed with dust, then it stucks the mechanism.
When serviced the watchmaker will see if some parts are damaged.
But a chronograph that stops when chrono is started is typical of a movement being dirty, for the chrono ask for additional power.

 

How fast have you been winding it. I have heard winding a watch too fast can have a huge effect on the mechanics inside....

 

The movement was overhauled about a year ago and I must have worn the watch maybe 10 times only. I normally wound the watch 40t turns each time.

 

Then it could simply be that there is too much tension on the chronograph transmission wheel. Your watch maker should fix it in a minute.

 

Thanks a lot for the advise omegastar.

 

See if some of the hands interfere, in certain positions the large minute hand can get caught by the minute counter hand or constant second hand which blocks the movement.

 

Thanks for the advise mac_omega. That could be a possibility so let me check on that.