Thanks so much for the replies. I've had the camera for many years, but I'm a little out of practice. The video (thanks for link) is no different than my technique. As for repair, the body flat fee repair is around 200 clams if I remember (
KEH?) and I've seen bodies (supposedly good) for $100 so it's hard to decide which direction to go if indeed it's a camera flaw.
Yup, it's hard to think about fixing it if bodies can be had for less. A quick search at
KEH turns up an M534S body, depending on condition, anywhere from $90 for Bargain to $168 for Excellent+
MAMIYA M645 1000S MEDIUM FORMAT CAMERA BODY - KEH Camera
I know what you mean about being rusty. I had my 645 on the shelf for almost a year because it had a shutter problem. Turned out to be a really simple fix and so I took her out to play about a month or two ago. I loaded the first roll backwards and didn't realize that I'd essentially "exposed" the backing paper until I was done (or thought I was done) with the roll. Of course, my very best shot ever was on that roll

But at least I didn't ruin the film so I can have another crack at the Best Shot Ever.