1.) Is gear visually damaged, 2.) can you spin the gear on the motor shaft both ways (bad)or does it spin one way and make the motor turn the other (good), 3.) a.) put starter motor body on negative battery post, b.)attach jumper cable to positive post, c.) touch other end of jumper cable firmly to small post on starter - gear should firmly move out as to engage flywheel (work that a few times to make sure it repeats), d.) touch jumper cable firmly to both starter posts at once - gear should jump out and motor spin. HOLD ON TIGHT - IT"S A PRETTY POWERFUL MOTOR. If you can get an extra set of hands, it helps.