Rebuilding floor jacks

[Motornoggin]

OK, I have three floor jacks. One is a Craftsman 2 1/2 ton HD model, one is a no-name quick rise unit and the other one is a small cheapo wal-mart special. Only the smallest one works, which really brings the suck. Can these things be rebuilt? Am I just looking at a couple of O rings or something? Is it even worth rebuilding these things? I have checked the oil and bled them, but that doesn't seem to help. Thanks.

[Grim Reaper]

If the cylinders and pistons are not scored then its just a matter of finding seals.

I have a 50+ year old monster made out of 3/4 plate and a 4 inch diameter piston rated 6 tons, 5ft long main body with a 30 inch lift and weighs about 250lb. Having problems finding the seals for it. The cylinder seals are fine its the seals on the valves in the pump where the real problems are going to be.

[dubbyx]

We've got a shop here that rebuilds 'em. I paid $50 to have my old blackhawk rebuilt a couple years ago after some jackass put motor oil in instead of hydraulic oil. Was well worth it and only took them a couple days.

Don't know how feasible it would be for a lesser model jack though.