How do you disassemble the small drive gear on the PE550?

The small gear (part # 530071258) is attached to the clutch drum with a right-hand threaded cap screw (remove counter clockwise with an Allen wrench). It is secured with Locktite. To keep the clutch drum from turning while you remove the cap screw you must remove the transmission case from the edger (three long screws that are very hard to see and accessed from the blade side). The clutch drum has four holes in it -- you will use one of them to hold the drum from turning. Insert a 3/16 to 1/4 in drill thru one of the holes and drill a hole in the plastic transmission case, but not into the grease chamber. To keep the drum from turning, pass a screw driver or other round tool thru the hole in the drum and thru the hole in the case. Use the screw driver as a lever to keep the drum from turning and back out the cap screw counter clockwise. If the drum clutch becomes out of round you will have to replace it (part # 530036665).