Where to send for service

Is there a list of people that can do a service/repair of a non-running Accutron? I have put it in "Find my Watch" but no dertimation yet.  It does say "N7" on the caseback which I understand dates it to 1975.   I know there's no way of knowing what it will cost but what is a range?  And are there common things that go wrong with these?  Thanks!