Park the mower on a flat, level surface. Turn the engine off, and allow any motor activity to come to a complete stop.
Remove the four hex bolts located at the upper corners of the engine housing cover with a socket wrench. Pull the engine housing cover off of the engine. Set it to the side.
Locate the pull cord mechanism, a small, circular spindle on the left-hand side of the mower.
Cut away the existing pull cord with scissors, if it is still attached.
Thread the end of a 10-foot length of heavy-duty nylon cord through the center of the pull cord spindle. Knot the cord around the circumference of the spindle, securing the cord in place.
Wind the new cord three times around the pull cord spindle, creating extra slack in the cord.
Pass the end of the cord through the pull cord hole in the engine housing cover. Pull the cord tight.
Reattach the engine housing cover to the mower by replacing and tightening the hex bolts.
Pass the cord through the rope guide mounted on the right side of the mower handle.
Cut off any remaining slack in the cord with a pair of scissors.
Tie the end of the cord to the plastic "T" handle included with the original pull cord. If you do not have the original pull cord, tie the cord to the center of a 4-inch section of wooden dowel.