Anyone know anything about the Ferris IS 3100Z? Mine keeps throwing the belt drive from the main pulley to the blades on the deck. By my eye I cant see any pulleys that are bent or out of alignment, I have bought new belts and it doesnt help. I see no adjustments I havent tried. The owners manual might as well have been written by a 5 year old with ADD. I'm THINKING it might be the fact that the deck is maladjusted on the chains, make it's angle too steep... but again, by my eye i cant see anything that sticks out.