Move the Weed Eater mower onto flat ground and stop the engine. Wait for the blades to stop spinning and lift off the rubber boot on the end of the spark plug, in the front of the engine.
Unscrew the rope guide on the mower's handle using the wrench and screwdriver. Disconnect the rope guide from the handle and set it aside. Unscrew the top starter cover with the wrench.
Turn the starter cover over to repair the rope. Hold your thumb on the pulley and unscrew the center bolt. Cut the starter rope at the base of the handle and the knot on the pulley. Unwind the rope and remove it from the pulley.
Fit the new rope through the center of the pulley, through the starter cover and through the starter handle. Tie knots at the base of the pulley and just above the starter handle. Wind all but 10 inches of rope around the pulley.
Hold the starter cover in one hand and twist a loop into the 10 inches of rope with the other. Wiggle the loop back and forth until the recoil spring hooks onto the pulley. Wind the loop and pulley four to six revolutions to put tension on the recoil spring.
Let go of the loop, but continue to hold the pulley in place. Unwind the starter rope and take your thumb off the pulley to rewind the starter rope. Add or subtract revolutions on the pulley if the starter rope handle doesn't stay tight against the starter cover. Reassemble the starter parts in reverse order.