Another vote for Paul Ebel. I have sent people and LF shutters to him for several years with very good results. As a matter of fact I have a shutter packed to send him today. I have not needed to use him for medium format, so I don’t even know if he does MF.
He has changed his address slightly. Also included is his e-mail. He responds quickly to that.
Paul Ebel Lens Service
PO Box 141
Menomonie, WI 54751