A lawn tractor is a bit more complex than your regular push mower. All the moving parts require some sort of maintenance during the mower's life. The belts, which move all these parts, are not exempt from repair. Over time, due to wear and extreme weather conditions, mower belts become hard, brittle and may begin to disintegrate. Replacing the mower belts every few seasons ensures the mower will not break, and prevents injury from malfunctioning parts.
Move the mower to a level service and engage the parking brake. Disconnect the sparkplug to prevent the mower from starting while working on it.
Lower the mower deck to the lowest position.
Clean the mower deck with a clean cloth, and if available, spray away loose grass with a pressure hose. Look at the routing of the drive belt and see if there are routing instructions on the mower deck, which many models have.
Remove the bolts holding the belt cover in place, using a socket wrench. There are usually three.
Reach under the front of the mower and remove the drive belt from the front drive belt pulley.
Disengage the drive belt from the mower deck pulleys, releasing them from the guards.
Reinstall the belt around the back pulleys first, finishing at the engine pulley at the front of the mower. Route according to the instructions. Ensure the belts are not rubbing against any of the belt guides.