if all functions work except lift this verifies your auxiliary part of the controls are working. If you pull the lift lever and hear the main pump startup then you know that is working. If you don't hear it start up check the switch or contactor.
On some of the older trucks they utilized the power steering pump for auxiliary hydraulic functions so that might explain why all your auxiliary functions do work but not the main lift. There is a distinct difference between the auxiliary and the main hydraulic, the sound would be obvious. The main pump motor would be very different than the auxiliary pump motor. (louder and more distinct).
Other possible causes:
your main function for lift is bypassing or working (not engaging) but you hear the pump motor start and run:
-i would check the main pressure relief valve and make sure the spring inside it is not broken.
-You also might want to put a pressure gauge on the main lift port and see what pressure it is getting if any, to verify. If the relief valve is damaged you will not get any pressure to the lift cylinder.
-Also if the splines on the pump shaft are stripped or the spider coupler is broken you would have no pressure, so, pull the pump off the motor and verify the splines/spider coupler are still in good shape.