Cub Cadet Lt1050 Belt Keeps Coming Off . Everything works but the pto belt is loose, it. Inspecting and tightening the belt is crucial because a loose belt is dangerous and can fly off at high speeds. OEM Spec Deck Belt Cub Cadet LT1050 LTX1050 LGT1050 LGTX1050 Mowers 954 from www.ebay.com Make sure deck is level.and pitched front to back.i would bet that the idler arm is bent,from when the first belt came off. I used it for a couple years and it's been broken for a couple years. There are a few things you should check on your mower deck to minimize the need.