The Stihl FS-55R trimmer includes a mowing head for trimming grass and weeds as a line trimmer. There is also a metal cutting head that installs in the place of the mowing head to make this a versatile tool. The metal cutting head uses a circular saw blade that cuts through limbs, large brush and small trees to clean up your property. The heads need to be removed to change to the other type of head for different applications of the tool.
Turn the Stihl tool off and let it cool slightly.
Turn the tool over so the head is facing upward and it rests on the ground on the handle end.
Wipe the head off with a towel to remove dust, debris and grass.
Insert a screwdriver into the gear head hole. The gear head is the lower most part of the head assemble and the hole is near the shaft of the tool.
Hold the screwdriver in the gear head hole as far as it will insert and apply upward pressure on it. Place one hand on the head and rotate it clockwise until the stop pin halts it from turning. The shaft is now blocked so that the head locks into position and will not turn.
Place a pair of adjustable pliers on the metal nut on the top of the head and turn it clockwise to loosen it. Remove the screwdriver from the gear head. Pull the nut straight off and pull the head straight off the tool.