Remove the belt cover located on the side of the tiller by removing the four self-tapping screws from the cover, using a screwdriver. Place the cover off to the side.
Lift up the spring-loaded idler pulley with your hand, then slip the tine belt off the "tine chain case" pulley located directly to the left of the idler pulley using your other hand. Remove the other end of the tine belt from the "two-step" engine pulley located to the right of the idler pulley. Release the idler pulley.
Lift up on the small idler pulley that holds tension on the reverse gear belt, which rests on the set of pulleys locate behind the pulleys for the tine belt. Slip the reverse belt off the outside sheave of the "wheel chain case" pulley, then slip the reverse belt off the "two-step" engine pulley.
Loosen the hex bolt at the top of the belt keeper that rests over the forward gear belt with a wrench, then rotate the keeper out of the way. Do not remove the bolts.
Lift the idler pulley for the forward gear belt, which mounts to the far right side of the belt, and slip the forward belt off the "forward engine" pulley. Then pull the belt off the inside sheave of the "wheel chain case" pulley.
Place the new forward belt onto the "forward engine" pulley and then onto the inside sheave of the "wheel chain case" pulley. Lift up on the idler pulley and slip the belt over the idler pulley. Lower the belt keeper over the belt and tighten the hex bolt.
Place the reverse belt onto the outside sheave of the "wheel chain case" pulley and then onto the "two-step" engine pulley. Lift up on the idler pulley and secure the belt to the idler pulley.
Place the tine belt onto the "two-step" pulley and then onto the "tine chain case" pulley. Lift up on the idler pulley and secure the belt to the pulley.
Place the belt cover onto the tiller and secure it with the four screws, using your screwdriver.