My Mamiya 7ii is there right now being serviced for the 2nd time. Bob Watkins is THE expert on Mamiya 6 and 7 and still gets parts from them. He said he still has a large stock of parts and will be servicing them a very long time.
That being said, the Mamiya 6 and 7 are not good build quality cameras. The lenses, however, are unmatched by any other lens I have ever used. Itís worth it if you want the best results you can get handheld. My photos rival my 4x5 large format camera.