I dropped the hydro pump from a 52' 8N I recently acquired due to the condition of the oil drained from the tractor. After cleaning the pump thoroughly, I reassembled with new gaskets, wear on the pump components did not seem excessive so I reinstalled into tractor. I also pulled the cylinder and piston, honed cylinder, installed new o-ring and leather ring on piston, reinstalled in tractor,filled reservoir with the correct Ford oil. Ran tractor for 15 minutes while working the position lever up and down to remove air from system, lift arms come up quickly without a load but will not lift a load. Any suggestion?