it sounds like you control valve maybe sticking. With the lift lever down, remove the right side access cover and you will see an "H" shaped contol fork that goes under the fluid level.WITH THE ENGINE OFF (NEVER REACH INTO THE COMPARTMENT WITH THE ENGINE RUNNING ESPECIALLY IF THE PTO IS CONNECTED), reach under the oil surface and feel for the bottom of the control fork. You should feel a "T" shaped control valve stem and the cross piece should be in the sockets on the bottom of the "H" shaped control fork. Now pull the control valve stem back and forth. If the lift is UP, when you pull back it will drop. It should move back and forth easily and smoothly. If it sticky or rough feeling it got some crap and corruption in between the control valve and control bushing.
Now start the engine and engage the pto/pump. Move the lift lever full up and observe the control linkage. You should see the bottom of the control fork move forward and the lift should rise. Now put the lift lever full down and the bottom of the control fork should move to the rear and the lift should drop. report back on what you find.
As the other rposter said, get a Ferguson Shop Manual. You can find them on ebay in pdf format or in paper back. They run about $20 for paperback and~$25 + for pdf. Do not waste your mobey on the IT manuals as they are not for beginners. Get the factory manual.