I replaced mower deck belts on two MTD riding mowers, 38" & 42" decks. Both belts I used the correct part nos. according to the owners manual. Both belts seem to be too short. The decks stay partly engaged, making the motor hard to start. Once started, the decks have to be engaged, if not engaged they smoke and burn. All belts I have found are made in Mexico. Could there be a size difference?