Hmm, I don't remove the governor arm when removing the sump but no matter, the static governor setting needs rechecked, re-set after removing/installing the sump anyway. Push the throttle arm on the carb to wide open position. whatever way this moves the shaft coming out of the block and the attached arm, clockwise in this case, move the arm as far as it will go while throttle is wide open, hold there while tightening the clamp holding the governor arm to the governor shaft. As you said, there is not much movement either direction.
Good luck,
Walt Conner
wconner5 at frontier dot com
PS: I can send you a Service Manual for your engine IF you like. Address below, out in proper format and remind me engine model number and what you want.