I had a broken Mamiya 6, with a cracked lens mount and intermittent shutter. I sent it to Mamiya USA who sent it back to me with a note saying it was too broken to fix. It sent it to Bob at Precision Camera Works. He made it like new at a reasonable price. I wouldn't hesitate to send him my 6 again.
One note about Bob, he's not real big on communication. In the six months he had the camera, I called and emailed several times but never got a response. I had pretty much given up on the thing when a woman called saying my camera was ready and what address did I want it sent to.