The pull-start assembly on a chainsaw contains a couple of parts that frequently break. The rope may break from wear or from dry rot caused by dampness, or the tension spring may wear out. The pull-start assembly is located behind the cover that is closest to the pull-start rope. Remove the assembly carefully, as the spring is under tension and may pop out of position.
Remove the screws holding the starter cover to the chainsaw and lift off the cover.
Remove any of the pull rope that is still attached to the spool. Use a pair of needle-nose pliers to pull the rope out of the spool.
Pull the assembly apart if the spring is broken. Remove the nut or cottar pin that holds the pulley to the shaft with a pair of pliers. Remove any remaining pieces of broken spring and insert a new spring. Replace the shaft with the nut or a new cottar pin.
Insert a new pull rope in the hole at the base of the spool. Tie a knot in the rope on the outside of the pulley so the long end is on the grooved side of the pulley.
Turn the spool in whichever direction tightens the spring, most likely clockwise, until turning the spool tightens during the turn. Turn the spool in the opposite direction one full rotation. Hold the spool to prevent it from retracting while attaching the handle to the pull rope.
Pull the loose end of the rope through the hole for the rope feed. The handle will be on that end once the cover is reattached to the chainsaw.
Push the end of the rope through the lower, or protruding, part of the plastic or rubber pull starter handle. Tie a knot in the end of the rope and pull the handle to the end of the starter rope.
Release the spool. Tug gently on the cord by the handle to activate the spring to retract the cord. The cord should pull properly back onto the pulley. If it doesn't, retighten the spring on the pulley by turning in the direction (usually clockwise) that tightens the spring. When the spring feels tight, turn the spool in the opposite direction one full rotation. Tug the cord to activate the spring.
Replace the cover on the chainsaw, securing it by tightening all the screws.
Put a drop or two of oil or spray a small amount of lubricant into the spring area of the pull start assembly before placing back into position to aid in lubricating the retraction assembly.