If you are talking about the helm pump not the piston. I got the seal rebuild kit from Trotac in Victoria a few years back. We have actually done a rebuild on the transom pump unit (duel helm system) twice now. The first time it took a good size three arm gear puller to break the wheel free from the shaft without causing damage to the pump. Don't lose the shaft key (small curved piece of steel), if you don't have a replacement.