recently acquired a B7500 that sat for a few years. The three point won’t lift against any resistance. I removed the cover, replaced the piston o-ring and the two under the control valve, replaced the o-ring in the flow control, and disassembled and inspected the. Control valve. Put it back together and still no lifting power. The flow control seems to work now. The lift and lock functions work but the arms can be pushed down by hand with the lever in the lift position. Have cracked the lines to verify fluid is present and it is. Tests have been done at idle and at pto rpms with no change. Thinking it might be a weak spring in the control valve. Loader functions as it should so the pump is probably ok. The lock function holds too. Sure someone’s had this before, just don’t want to throw unneeded parts at it.