Hi all this is my problem I have this model 108
hampden and after cleaning and assemble
the watch will work for a while and them the
impulse pin/safety finger on a roller will just jump
out of fork .
what is wrong?
Thanks for your help.

Hi Peter,
I had a Hampden 108 that did the same thing. Take a bright light and look at the top of the balance staff where it comes through the crown or upper jewel. Apply very light pressure on and off the balance wheel to while watching the top of the balance staff and see how much play if any there is. Mine had too much play and after replacing the upper jewel everything was fine.

If that is not the problem I have not got a clue.
Harry