Has anyone ever overhauled a hydraulic jack? I imagine it is similar to rebuilding a master cylinder and/or a brake caliper, but where do you get the parts? I was at the local flea market today, and saw a nice sturdy-looking 3 1/2 ton jack, made in China but branded "Michelin" with the Michelin man on it and everything. The guy wanted $50 for it. To make a long story short, after several people looked at it, it was determined that there is something wrong with it, as pumps right up with no load but won't lift any weight, so the guy ended up giving it to me for free, so he wouldn't have to take it home. I would like to fix it, if possible, because it seems to be a decent quality unit, and not even that heavily used---apart from some overspray, and a few minor scratches, it looks almost like new. Any suggestions would be much appreciated.