The polycut head on a Stihl FSE 60 electric trimmer can gradually wear down from the friction caused by running it over rough grounds at high speeds. The head uses marks to show when it is worn down and needs to be replaced. These heads allow you to either install plastic blades or a nylon trimmer line. It should only be replaced with another Stihl polycut head, as other head attachments will not fit this trimmer.
Turn the motor off and unplug the trimmer from the power source. Never work on an electric device when it is plugged in.
Flip the trimmer upside down to service the head. Hold the trimmer steady and push down the cap while turning it counterclockwise until it springs up. Remove the cap and the cover from the head.
Unscrew the spool counterclockwise and remove the spool and spring from the head. Pull the mowing head off the metal stub. Put the new polycut head into place. Push down the spool and spring.
Push down on the cap and cover and tighten the cap clockwise. Plug in the trimmer to use it.