With zero pressure in the struts, you've got to lift the whole weight of the top and it's heavier than hell!

It may be worse than that: If the piston seals failed but the rod seals held, all the gas pressure is now on the annulus or ring-side of the gas spring thus keeping the rod from extending swiftly. Applying up-pressure on the lid and then waiting may do the trick.
Good luck!
Uli
'AS'