Novice repair attempt here. Dryer started making a thumping sound. Disassembled and cleaned out all the dust. Found that when I spin the drum around very slowly, with very low force applied, it sticks so that I have to apply just a little more force to get it over the hump, and then the thump sound occurs. I marked the smaller inner belt and found that the sticking occurs at the same point on a 360-degree rotation of the pulley -- indicating the problem is with the pulley itself and not with the drum mount (which has a larger diameter) or the motor (which has a smaller diameter).
I tried removing the smaller belt could not reproduce the problem with just the drum driving the pulley. So it seems like some combination of forces from the two belts are causing the pulley to bind.
Does that sound right?
Do I just need to replace the pulley? Is it going to seize up, or can I just let it go like this indefinitely?