Hello guys. I have a Yale GLP040RDNU it's a '95 truck. The steering is hard/ no power steering when truck is not moving but hydros ok. You move half an inch either fwd or rev, steering is ok. Jacked it up, ram ok/ not bent, drag link ok, king pin ok, everything mechanical ok. Overhaul steer cylinder thinking possible piston seal- same thing. Replaced orbital thinking that was it- same thing. Can't be the pump since it picks up 3000 lbs no problem. Any pointers?