Have you been servicing this lift before this issue started or is this the first issue you're servicing on this lift?

Reason for this question is- are you sure the main hoist cyl hasn't been altered/replaced?

I have a triple stage lift I service where the bottom of the main barrel got dented- the cyl had the packing at the bottom of the ram only w/ only a wiper in the upper gland nut. With the barrel being dented the ram wouldn't go past the dent, keeping the forks raised about 6". I had my hydraulic vendor re-machine the gland nut for a full packing & removed the packing from the bottom of the ram. After this alteration the ram went fully down, past the dent & the upright worked great, as long as you didn't mind the secondary cyl's raising first w/ the main cyl extending only after the secondary channels were fully extended.

Had to revert the cyl back to it's original configuration & have a new barrel made. Is it possible someone tried the same scenario on this upright?