When you are mowing grass with a John Deere lawn tractor and the mower suddenly stops moving, there is a good chance that the transmission drive belt has broke, and you will need to replace it. It is always a good practice before the mowing season to check the drive belt under the lawn tractor for tears or frays. With a few tools and a new belt, you can replace the transmission drive belt quickly and easily.
Set the John Deere lawn tractor's deck-height lever to the lowest setting.
Kneel next to the left side of the mower deck.
Put a 15mm wrench on the idler pulley in the centre of the deck. Push the wrench forward to remove tension in the transmission drive belt. A spring is attached to the pulley as it acts as the tension pulley for the transmission belt and the belt around the two outside pulleys that run the deck blades.
Slip the belt off the top of the idler pulley and off the transmission pulley on the rear axle of the John Deere lawn tractor.
Slip the new belt on the transmission pulley and around the idler pulley. Release the idler pulley to put the proper tension back in the belt.