Remove the Deere's spark plug wire with pliers.
Use an Allen wrench to remove the bolts holding the starter assembly in place. Pull the asembly off.
Cut the end off the old rope near the starter handle and remove all the old rope from inside the handle. Remove the spring from the starter assembly carefully by hand or with pliers and then unwind the old starter rope.
Slip the end of the rope into the starter assembly notch and then wind the rope around the assembly. Reinsert the spring with the pliers.
Slip the other end of the rope through the starter assembly hole and then through the rubber handle. Tie a knot to secure the rope inside the handle.
Pull lightly on the rope to make sure it recoils properly.
Attach the starter assembly to the side of the trimmer and replace the bolts with the Allen wrench. Attach the Deere's spark plug wire.