Check for resistance in the rewind mechanism. If this is binding it will cause something similar to what you are describing. It's also possible that the advance lever is loose on its spindle, or that something below it is loose. In that case you'll need to pull off the top plate and investigate. For starters, though, I'd put a drop or two of Ronsonol on the extended rewind spindle and spin it around a bunch of times. If it feels noticeably smoother, clean it with more Ronsonol and cotton swabs, then a tiny dab of silicone grease or (in a pinch) lightweight oil.