Mamiya C3 TLR maintenance

I was recently given a Mamiya C3 that I would like to shoot, it however has one annoying problem that is making that difficult (besides a sticky shutter, but that I can handle). The camera advances, and the shot counter works perfectly in the "multi exposure" setting, but if it is set to "roll film", it will often work fine for 1-3 shots, then it fails, letting me advance to the end of the roll. Again, oddly, the multi-exp setting works perfectly.

Anyone know what I should take a look at on this camera? I can't really justify the cost of a CLA at this time, but I have decent technical knowledge and abilities, so perhaps I can fix this issue with some advise.

Thanks.

If it makes you feel any better, I had the same problem with my C33, and it was a quick and easy fix. (It was also free, since the camera was still under warranty from the repair shop from which I had purchased it.) It had something to do with a missing screw inside. I'd get it looked at and at least get an estimate. They are super cheap cameras these days, however, so keep that in mind.

The shutter on the lens is also now stuck open, anyone know a place that would do a CLA on the body and lens, although, with the low cost of just buying another one, I may not. I just hate to see a good camera go unused.

I think most camera repair joints would charge for two repairs since it's two separate items.
Since you're in Chicago, send me a PM & maybe we can meet up & I'll have a look at it.
I used to repair cameras for a living until I found out how generous the Post Office was.

Well, it seems to be alright now. Some moderate heat freed the shutter, and the times now seem to be spot on, which was never the case. And the advance problems seemed to be caused by the back not seating firmly. I'll put some rolls through it again, and see how it fairs actual use.

All the 'roll film' setting on the body does is prevent accidental double exposures. Since I have at least one lens that pre-dates the C3 and allows the camera's body release to move even when the shutter is not cocked, I have left the camera set on 'multi-exposure' forever with no problems.

Bob