When I engage the blades, the belt is popping off - usually after I start moving forward. I have replaced the belt. I just ordered a new idler arm (part # 197249 ) as the existing one seems a bit bent and that pulley seems to point downwards. This is only the 3rd season I've had it and the part doesn't look worn, but it's possible something knocked it out of whack. Could it be something else? The belt doesn't have a TON of tension, but I noticed it seemed a little out of whack with the idler pulley, so thought that might have been doing it.