the watch is fine except for the mainspring. I don't want to send the watch to Audemars Piguet for a ground up restoration for obvious cost reasons. If anyone knows a source for such a part I would really appreciate your help.

If you post the measurements and end type someone may have one.
J Smith

My watchmaker only told me the caliber number of the watch. It is a super thin AP from the mid fifties. Watchmaker said it is the "thinnest mainspring made" with a very unusual end type attachment. Hope that might help.

Go to
www.dashto.org
Tom Mister has one that is .5 MM wide and others.Maybe he has one to fit your watch.
J Smith

Thank you for your help. Regards, Mike Loggins