Park the tractor on a level surface. Set the parking brake and remove the key from the ignition. Study the belt replacement guide decal located underneath the left foot board for proper belt routing instructions.
Remove the mowing deck by first moving the attachment clutch lever to the disengaged position (toward you). Move the attachment lift lever all the way forward to lower the mower housing to its down position.
Crawl beneath the tractor and roll the drive belt off engine pulley (it hangs directly beneath the engine). Remove small retainer clip that holds the clutch spring to the pulley bolt located at the center of the mowing deck. Remove the large retainer springs (two of them), then slide the belt collar away from the mower housing and off the housing bracket.
Disconnect the anti-sway bar rods from the chassis brackets by removing the retaining cotter pins. Disconnect front links from the mower deck by removing retaining cotter pins. Disconnect the suspension arms from the rear mower deck brackets by removing the two cotter pins.
Move the attachment lift lever all the way to the forward position to raise the mower suspension arms to the full up position. Slide the mower deck out from beneath the tractor.
Crawl beneath the tractor and roll the drive belt off of the stationary idler pulley and the clutching idler pulley. They are both located immediately adjacent to the engine pulley. Be sure the belt is already away from the engine pulley, as well.
Push the drive belt slack toward the rear of tractor. Remove the drive belt from the trans axle pulley by taking it over the trans axle pulley while compressing the movable belt keepers surrounding it. Remove the old belt from the tractor by pushing it clear of the center span keeper (located beneath the trans axle pulley).
Install a new drive belt by following the reverse of the instructions for removal. Test the tractor and mower for normal operation.