Old 1960 Hyster Mod H60B serial # B5D 2534D. This is an old forklift, the power steering has quit working. We had the power steering cylinder rebuilt and when disconnected from the steering it operates in and out, but there is no steering assist when driving. Fluid is up and all other hydraulic functions seem to work. The valve on the steering column maybe the problem, but we are told no rebuild kit is available. Thanks for any help you can give.