help us help you.. any backstory on this?
is it a mechanical problem like a bend cyl rod or damaged loader frame that physically won't let it lower?
if not that, have you tried running hte spool thru range of motion with engine off and letting it exhaust?
Have you thrown a towel over the line fromt he spool to the lift cyls and then cracked the connector with a wrench to see if it starts leaking and lowering the loader?
tell us what you have, and what you have already done.
pics help.