Open the gas cap and make sure there is gas in the rototiller's tank. If the gas tank is low, fill it and then try to start the rototiller.
Pull off the rototiller's spark plug wire and use a spark plug wrench to remove the plug. Install a new plug and start the rototiller.
Remove the air filter cover on the rototiller and take the filter out. Tap the dirt out of the filter or replace it with a new filter.
Remove the two screws and one nut on the rototiller's belt cover, with a wrench and a screwdriver.
Press the idler belt pulley straight forward and slip the reverse drive belt off. Once it has cleared the idler pulley, remove the other end from the variable speed pulley.
Push the machine's shift lever to forward position and then remove the forward drive belt from both the variable speed pulley and then the engine pulley.
Slip the new forward drive belt onto the engine and variable speed pulleys. Place the reverse drive belt over the variable speed pulley and then pull the idler belt pulley backwards and slip the belt over it.
Replace the rototiller belt cover with the wrench and screwdriver.