Your Stihl power tools with two-cycle engines utilise a pull-string, or recoil starter system to start. It is not uncommon for dirt, tree bark or other debris to get stuck inside your recoil starter. When this happens, your recoil starter can get jammed up pretty badly. The only way to repair this is to take apart your machine, remove the debris and then rewind your recoil starter by hand.
Remove the screws on the outer cover of your Stihl. There are four screws located in each corner of the cover. Remove them with a Phillips screwdriver and set the screws and cover aside.
Pull the hand guard down and out of the way. Also remove the fan housing to expose the pull start rotor.
Carefully remove the spring clip with a pair of needle-nose pliers.
Use your wrench to remove the bolt holding the rotor in place, and then slide the rotor out. Unwind the starter rope, and clear out any debris that may be lodged inside the rotor with your screwdriver tip.
Slide rotor back in place, and then screw retaining bolt back into place with the wrench. Turn the rotor back and forth a few times to make sure the rewind spring engages.
Reinstall the spring clip with your pliers. Turn the rotor by hand six revolutions in the clockwise position. Once you have done this, turn it back counterclockwise for one revolution to loosen tension in the spring, as too much tension can cause the spring to pop.
Set the fan housing and hand guard back in place. Also place the cover back on and reinsert the screws.