Troy-Bilt mowers utilize centrifugal force applied by a pull string and a recoil pulley to grip the engine shaft for starting the engine. Over time, the recoil spring can start to weaken; and when you pull on the recoil string, the spring does not retract the string fully. When this happens, you must remove the pull start system and replace it with a new one.
Remove the recoil housing cover by first locating the mounting bolts that secure the housing to the top of the engine then by removing them with a wrench. If necessary, on some models, you must remove the bolts that hold the gas tank to access all of the recoil housing bolts.
Pull the recoil pulley off of the motor shaft.
Unwind the recoil string from the pulley. Locate the knot on the bottom side of the pulley and untie it or cut it off with a pair of scissors. Set the rope off to the side.
Pull the spring off of the motor shaft then slide the new spring onto the motor shaft. The spring has a pin on each end. Make sure the pin seats into the hole next to the motor shaft.
Place the rope into the replacement pulley and tie a knot in it. Wrap the string around the pulley, leaving approximately 3 inches unwound.
Slide the pulley onto the motor shaft, line up the pin in the spring with the pin hole on the bottom of the pulley then seat the pulley over the spring.
Reattach the housing cover with the original bolts and the wrench. Reattach the gas tank if necessary.