Just purchase a used Craftsman Lawn Tractor Model # 917.271.08. Half hour of driving and the ground drive belt slipped off. Had to cut the belt off as it wrapped around the pulley shaft on the transaxle. Got a 82 inch x 1/2 belt, and it slips off after a few minutes. The OEM belt # 140294 is specified as a 82". Any ideas what to look for to keep the damn belt on?