I recently removed one of the "lift-o-matic" cylinders (looks like a skinny shock absorber) that supports the hood from my '96 E320. When I detached it from the bolts that hold it in place, it immediately extended to it's full length and appears to be stuck. I can put my full weight on it and it will not compress.

Does anybody know if there is a trick to compressing this cylinder or is it likely that the unit is damaged and needs replacing?

Any thoughts would be appreciated.