Bought a used ALRO steel 10K lb truck with 209 inch lift mast from a private guy who "refurbished" it with cyl. head work, tires, fuel line and regulator, etc. Lifting 6000 lb. with a lifting bar gets halfway up and stops. Put the load on a pallet and it gets a little higher. My lifting center is 24" where it belongs with the bar. He gave me a "loaner' and it performed perfectly. He lubed the mast and 'adjusted' the pressure, same thing. I have heard of a one time hyd. 'fuse' to limit down travel in a failure, but I believe in data. If my pressures are ok than I can look to a mechanical problem. Don't know where to test though. Sound right folks?