At some point you may need to replace the deck belt inside your Craftsman riding mower. There are two main belts in your mower. The transmission belt is part of the engine and rarely fails. The deck belt, on the other hand, is lower in the carriage and more likely to be nicked and split while you're mowing the lawn. There's a good chance you'll split a deck belt more than once during the life of your mower. Luckily, replacement belts are widely available, and no tools are required to install the belt in the mower's pulley system.
Take the keys out of the ignition to make sure there's no chance the mower can be turned on during the repair.
Lift the seat to check the serial number for your riding mower. Replacement belts are sold by serial number, so you'll need this to purchase the right belt. Buy the belt at a hardware or home improvement store. Transmission and deck belts are replaced the same way.
Locate the replacement diagram that illustrates the mower's pulley system. Most mowers have the diagram printed right on the mower carriage. It's also in the owner's manual. It shows you where the pulleys are located and where the belts go.
Slide the deck setting all the way down to the lowest position so you can easily access the pulleys. The deck setting lever is on the mower's dashboard. In most cases, you simply slide the lever all the way down.
Remove the old, split belt if it's still attached. You'll notice there are retention bars and clips that keep the belts in place next to each pulley. Some pulleys also have springs that open and close. Make sure there aren't any torn pieces of the old belt stuck anywhere.
Pinch the new belt to squeeze it between the retention bars and the pulleys. As you go from one pulley to the next, make sure the belt is firmly seated inside the "V" space of each pulley. If there are clips on a pulley, open and close them to make sure they don't snag the belt.