I bought a 2.5 ton hydraulic car jack and have used it for three years, generally not for lifting cars. I used it to jack up the corner of a sagging porch but for the last few years I've been using it to lift fallen trees so that I could cut them with the chain saw without binding.
I tried jacking up the end of a fallen tree today and it wouldn't move. When I pumped the handle without a load, it lifted fine, but with any application of weight, it's useless. I tried adding more hydraulic fluid, but that didn't help.
Looks like some valve or compression ring is worn out inside the pump mechanism. There's no easy way into the unit, it seems. Unless someone knows of a simple repair for this sort of thing, I'll just junk it and get a new one, as they're not that expensive.
Thanks for any clues.
Paul