Allow the lawn mower to fully cool down. Pull the rubber spark plug wire from the spark plug. The spark plug is typically located on the side of the engine that faces the push handles of the mower.
Use either the 7/16-inch end wrench or the ½ -inch end wrench to remove the three bolts that hold the starter housing to the engine. The make and model of the mower engine will determine the size of the bolt heads, and which wrench will be used. Turn the wrenches in a counterclockwise direction to loosen the bolts. Remove the bolts with your fingers. Set the bolts in a safe location so you do not misplace them.
Lift the starter housing from the engine. Lay the housing upside down on a flat and firm surface. Observe the plastic pulley that has an internal tension spring.
Wind the plastic pulley in a clockwise direction. This will place tension on the internal spring with every revolution of the pulley. Tighten the spring and pulley until you can no longer turn the pulley.
Back the pulley off just enough to align the rope hole in the pulley with the hole in the top of the starter housing.
Place one of the handspring clamps so it will hold the pulley to the top of the starter housing. Set the second handspring clamp directly across from the first one to firmly hold the pulley in place while it is under the spring tension.
Use the pocketknife and make a clean cut to the broken end of the pull rope. The end goal is to have the frayed end of the rope as tight as possible in the weave of the cord. If the end of the rope is too frayed, apply a small flame to the cut end with a lighter or matches. The heat from the flame will melt the loose frays and make the end of the rope easier to feed through the holes.
Feed the cut end of the pull rope through the hole in the starter housing. Use the needle nose pliers to help you in moving the end of the rope, and feeding it into the small hole on the plastic pulley.
Pull approximately 8 inches of the rope through the pulley hole. Tie a knot in the end of the rope. Pull the rope back through, so the end of the knot is resting up and against the hole in the plastic pulley.
Remove the two handspring clamps, while holding the pulley with your other hand. Allow the spring tension pulley to slowly rewind the rope.
Replace the starter housing back on the engine. Install the three bolts. Secure the spark plug wire over the spark plug.