I have a '85 Troy bilt tiller model # 195432 which needed to have the main power shaft replaced. I was able to disassemble the transmission and order new parts. On the new drive shaft the bearing and cup nearest the worm is already mounted. There is another bearing and cup that needs to be mounted but I'm not sure how to do it w/o damaging it because the shaft widerns slightly where the bearing rests. I suspect this is where the bearing locks into place on the shaft but how do you get it on there?