Disconnect the spark plug wire from the spark plug to disable the Montgomery Ward mower while you work on it.
Set the parking brake and lower the mower deck to its lowest position with the deck adjustment lever. According to Montgomery Ward, it is not necessary to remove the deck from the lawn tractor to replace the belt.
Locate the engine pulley mounted directly under the mower. You can locate it by lying on the ground in front of the mower. Remove the bolts that hold the belt guard over the pulley with a wrench, and then place the belt guard off to the side.
Remove the belt guards from the mower deck with your wrench.
Pull the belt off the engine pulley, and then remove the belt from the pulleys on the mower deck. It is vital that you reinstall the belt correctly. If you aren't sure that you can remember the belt routing on the deck, draw a picture to help you.
Place the new belt onto the deck's pulleys, stretch the belt to the front of the mower and place the other end of the belt onto the engine pulley.
Place the belt guard over the pulley, and reattach it with the bolts and a wrench. Reinstall the belt guards onto the mower deck.