If it has a clutch, you will have to prevent the driveshaft from turning. See if you can put something thin in the access holes on the arbor (round plate) below the geardrive just above the head to lock it up and turn the whole string assembly off. I don't know if the threads are right-handed or left-handed, (probably right) If the unit has no clutch then you will have to stop the driveshaft AND ENGINE from turning. Remove the spark plug. Rotate the engine so the piston is down. Insert a length of clean pull rope into cylinder so as to jam the piston and it returns up and turn the string head off the threaded end of the shaft.
Roy, November 2009
