TO20 Lift questions

My neighbor has a TO20 with a lift issue. I suspect at some point that he tried to lift something to heavy, like a 55 gallon drum(s) of feed, water something. In any event the lift tries to lift a load but can't even if he rev's the motor. The serial number is TO-3749. I see that there are 2 different relief valves, which would be correct? Also which piston would it have? Are they the same as the Ford? I've searched but haven't found a definitive answer unless I'm not asking the correct question.

I assume your friend knows that the pto must be engaged in order for the pump to run an provide flow for the hydraulic hitch.

Pull the right side access cover. WITH THE ENGINE OFF, reach down into the oil and feel for the "T" shaped control valve stem. Make sure the ends of the "T" are in the sockets of the "H" shaped control fork. Try to push the assembly forward and pull it backward. It should easily move fore and aft a total of about 1 inch. If it"s sticky then some crud got in there and is restricting the movement of the valve.

If the valve moves freely, start the engine (UNDER NO CIRCUMSTANCES SHOULD YOUR HANDS BE PLACED IN THE HYDRAULIC COMPARTMENT WHEN THE ENGINE IS RUNNING.)Look at the aft end of the pump for lots of turbulence. if you see that it could mean a stuck open relief valve. Look around the end plates of the pump for oil leaks indicating blown side plate gaskets.Put the lift lever in the lift position. The "H" shaped control fork bottom should push the valve forward and the lift should rise. If that action takes place, observe the lift cylinder area and look for leakage from the lift cylinder. anything more than a few drops is a leak using a flash light and a mirror, try to observe the right front corner of the hydraulic compartment where a vertical tube runs from the pump to the lift cylinder. There is a seal where the tube goes through the flange to the lift cover. Make sure it is not leaking there.
report back on what you find.

Thank you I will report what I find