Are you talking about the valve in the console, or the "motor"? The steering valve ports, IIRC are o-ring boss. You need to use hydraulic o-rings that have a higher durometer rating than the cheap nitrile o-rings that cant handle the pressure. If your base gasket is leaking, either your return is plugged somewhere causing an over pressure situation in your valve, or you have a blown gasket. If its in the steering "motor", again, wrong o-rings, bad gasket, or plugged on the return side.