When the tractor belt that drives the mower deck on your Craftsman mower comes loose, you must adjust the belt. A loose drive belt is typically caused when the belt begins to wear during normal operation of the mower. You can adjust the tractor belt by removing the old mower drive belt and installing a new one on the tractor.
Move the mower into a garage or other area that has a level floor.
Lower the mower deck all the way to the ground by pushing the attachment lever on the side of the tractor forward.
Locate the belt tension rod that is on the right side of the mower deck.
Disengage the belt tension rod by removing it from the locking bracket, which will loosen the tension on the belt to make it easier to remove.
Remove the screws that are used to secure the mandrel covers to the mower deck. A mandrel cover is on each side of the mower deck that covers the mandrel pulleys.
Remove the drive belt from all of the pulleys on the mower deck.
Place the new drive belt around the mandrel pulleys and around the idler pulleys. The idler pulleys are the ones that are next to the mandrel pulleys.
Place the belt around the electric clutch pulley located on the front of the mower.
Set the mandrel covers back in place, and tighten the screws with the screwdriver.
Engage the belt tension rod by placing it back into the locking bracket.