Not a Mamiya C330, but I had the same winding problem with my Mamiya M645, (maybe they have a similar winding mechanism) -I took it to our local (un-named) camera repair shop, and even though they supposedly repair old cameras, they said they couldn't figure it out, charged me $40, and sent me on my way. Turns out, they never even opened up the side of the camera. I carefully removed the side panel and the base to the winding lever, and the problem was obvious. A tiny "v" shaped spring that readies the shutter when the arm makes a complete cycle had broken (and disappeared) -I was able to fashion one out of a very thin rigid piece of wire, but it turned out to be too strong, so when you got to the end of the roll, it wouldn't stop engaging the shutter on each revolution, and I had to hold down the shutter button to wing the film off the spool. In the end, I found a "for Parts" Mamiya body on the web for $40, and easily extracted the spring and replaced it in my camera- works like new. -As far as the shutter leaves, a little Naphtha on a q-tip should be able to clean out the gunk.