I have a troy bilt tb30. I decided to change all three belts. Upon doing this I noticed the old drive belt that goes to the crank was rubbing the top of the rear end. It has actually wore a groove. After I removed all of the belts I checked all of the pulleys and they were fine. Tight but free and no play in them. I replaced the belts and the new belt is doing the same thing. Has anyone ever experienced this and how did you fix it?