I bought an older dump truck, it's a 76 chevy c30 with a 454. The problem is the electric dump wont lift a load of mulch. I looked at the cylinder and it doesnt appear to be leaking, what else should I check or change before I take it to a shop. P.S. It dumps empty and with a load I can get under it with another person and push with my legs while some1 hits the button and it lifts. Any ideas?