I've don't his about 5 times trying to fix the rubber puck isolator the gears nest in, they keep breaking after I epoxy the deteriorated ones. Well i finally found the culprit. The rear guide roller was broken so the window cocked in the tracks and licked up, taking the gear with it. I replaced the roller (delicate 'operation') and now the window travel is smooth as silk again after I replaced the broken rubber puck with a junkyard pull.