Switch off the Craftsman tiller's engine and wait for any moving parts to stop. Position the tiller on level ground. Unfasten the rubber boot on the tip of the spark plug and move it to the side where it won't contact the plug during repairs.
Unscrew the starter cover, on the front of a Craftsman tiller, and take it off. Turn the starter cover to work on the starter assembly, including the pull cord. Try pulling the cord off the rotor. Cut the cord off at the handle if it won't pull out. Move onto checking other areas if the cord does come out.
Cut the cord at the knot in the base of the rotor. Take the cord off the rotor. Unscrew the bolt on the starter post and remove the bolt, washer and rotor from the cover. Turn the rotor over and wedge out the recoil spring using the blade of the screwdriver.
Check the recoil spring for damaged tips or signs that it's stretched out. Check the rotor for cracks or any other damage. Replace the rotor or recoil spring if they are damaged. Reassemble the starter assembly in reverse order.
Spin the flywheel with your hand if the recoil starter assembly isn't the problem or if the problem continues. If the flywheel doesn't turn, the key may be sheared. Contact a Craftsman service technician for flywheel repairs.