I was turning a candle holder yesterday, at about 800 rpm. These things are about 3.75" in diameter once I get them rounded off, and I was at this point, when I found that the roughing gouge was stopping the piece, without a lot of pressure put on the gouge. I suspected the belt may be loose, so I took the cover off, blew away the dust, and found that the drive is looking even better than it did the last time I looked at it. Previously, it had started to become loose at about half speed, so I didn't use it above 1200 rpm (faster speed scare me ) Yesterday, it was tight at all speeds, with about 1/4" deflection if I pressed down on the belt. The belt appears to be in good shape with no cracks. The pulleys operate smoothly, and the whole thing looks good from 500 to 2500 rpm.
So, I'm a bit stymied as to why the work grabs and stops like that. I could just take less aggressive cuts, I guess, but cutting through a 4" blank to reduce it to about half that size in the middle takes a while, and tries my patience. I've just got started on this project again, and I am anxious to get it going smoothly.