I have a porter cable 333 variable speed random orbital sander. One day it smoked and quit being "random". I took the pad off to find the belt broken and the plastic around the screw and bearing you see in the left of the below picture was melted. I ordered a new belt and plastic base, but something is not quite right The screw in the bearing that holds the pulley belt is reverse-drive, but it either is too tight to let the bearing spin or it is loose enough to allow slop that also results in the bearing not spinning. Either way, the belt is pulled along the bearing and creates friction, which was presumably the caue of the previous failure. When I turn it on at low speed it neither spins nor moves the belt at all, and at higher speeds it will spin and move the belt, but not the bearing, obviously resulting in the same heat generation. if I remove the belt the center arbor continues to spin, but is not pulled to make it "random". I checked the parts diagram again and again and I don't see that I can be missing anything, but am not sure how the bearing and belt are supposed to behave. Can someone please advise? Thanks so much and sorry for the rambling.