ok i think i have an idea its one of those throttle springs. not the spring on the side of the pull cord where you grab the metal latch that activates the lawnmower but on the other side of the motor after i removed the top casing it seems to not hold still its a real tiny thin spring . it seems to control a pivot thing or an armature i guess thats the trottle peice, because when i push it with that screw drive and hold that peice in place the motor is wide open and strong like a champ, but when when i let it run on its own its wavering, so maybe need to wrap it just right with a clothes hanger