Okay, I am at a loss... Can't figue this. Hopefully someone can help me a bit further along. I got a Mamiya 645 (original model) in the mail. Looks nice and it all seems promising. However, it turns out I can't get it to fire the shutter, except by winding it with the knob. I looked in the manual, tried it with film in single, tried it in multi with film, tried without film in any imaginable variation I could think of. No amount of pressure on either of the shutter buttons makes any difference. Well, after all this, I removed the knob and when I inserted it again and wound on it so that it gripped onto the camera, I could see that the upper shutter button moves. When I try to wind it onto the next frame, it seems okay to wind until there's some resistance. If I then turn it a little bit further, the mirror and the shutter moves. I guess it should stop just there, but it's not. It's like the shutter opens and closes by winding on, but not pressing the shutter button. The manual mentions a red button/mark where I should insert the knob, but there is none, so I don't which way it should sit to be correct. Would that matter in this case? I was thinking along the lines that if it was inserted incorrectly, it would activate some kind of function for the winder accessories. Yes, I am thinking it is busted, but hope springs eternal, right?