Run it and look at the hydraulic oil. IF it is foamy looking , like I think it will be. You have a valve leaking on the high pressure side. So the lift will not lift and the oil gets foamed up and runs out the fill hole. If it is you will have to take the lift controls valves apart to see what is wrong.
I have not had one of them apart in 25 years or more. So I can not tell you off the top of my head how/what to do get it apart. I worked on a fair amount of these back in the late 1980s as guys started collecting them and wanted everything to work.