I'll give it a go. Make sure your pulleys are in perfect shape. If they are pinched, spread, or bent, that belt will shake like a wet dog. When the deck is lowered and the belt has to work on a different plane, the problem gets worse. Also, be sure you are using the correct size belt. Very obvious, but I've seen 1/2" belts where 5/8" should be, etc. Hope this helps. I take a 3"X5" note card and use it as a gauge. With a felt tip marker mark a spot on the pulley and the card where the top (or bottom, whatever's easy) and then rotate that pulley. Voila! Instant, easy visual reference.:smile: Good luck, let us know how you do and what you find.