Frank Marshman runs a shop called "CameraWiz" that's advertised in Shutterbug for ages, and he's a real craftsman and a real gentleman.
He's worked on all my classic Bronica stuff and refurbished a folder or two, some rollfilm backs for LF cameras, and a few other custom things for me like an adapter for using Canon FD macro lenses on my Bronica (bayonet-to-bayonet!). He is particularly recommended for old Bronicas and Ilex shutters, but he can also do things like machine new parts for all sorts of cameras. If you give him a project he'll often come up with ingenious solutions, and when he hasn't been able to repair something for me, he hasn't charged for it, even if he put in an hour or two of labor.
He maintains shutters for Michael Smith and Paula Chamlee, Sally Mann, and others.