Dear lou. Do you have one or two hydraulic pumps. If there are 2 pumps then one will be for the lifting and the other is for the steering. If you have a steering pump, please check whether is there any oil coming out from the discharge side. If there is no oil then problem with the pump. If there is oil, please check whether oil is going into the torque generator. When you turn the steering handle, oil will be coming out from the steering valve to the steering cylinder. If oil is going into the cylinder and the wheels do not move then you can look at the steering cylinder seals. Hope this information help. If you have only one main hydraulic pump then it will be advisable to look at the priority valve