Now that's a thread resurrection if I ever saw one. (3 years 10 months and 12 days!)
My 6 hasn't had any problems and I haven't done that much research, but I would have though Mamiya could fix it. They have a very nice HQ in Tokyo and happily worked on my 645 Pro TL a couple years ago even though it was long out of production. Have folks actually confirmed that mamiya will not or cannot do this repair?