Yep, it grounds thru the block. Hook up a ground clamp to the starter body, and hot wire to the big battery terminal on the starter. Then do a jumper from that terminal to the small terminal on the solenoid. Careful, it will kick out and twist a little when it works. That will tell you if the starter is good. Or, just take the starter to an AutoZone, or someplace like that, and they can test it for you. Either it works, or it doesnt, so I would say the starter is either bad, or you have a bad wire somewhere.