My new Pentax 645 has got an issue.. I throw film in, it makes a screeching buzz for about 20 seconds, then stops... It won't shoot. I turn of, turn on, does the same thing. I open it up, the film has never advanced.... When I was able to shoot a roll or two in it, the winder made smaller wimpers of that screeching noise during advance... Is the winder just hosed?? If so, is it a common issue with these beasts?? Does anyone think it is repairable? Will it be worth it?