I've got a 2 1/4 ton Sears hydraulic floor jack. I've had it for a while and first used it to hold up the transmission on my 125 cub as I split the tractor. I am all done: new driveshaft with new front and rear couplers, trunion bracket repairn new grass screen on the motor etc. Last evening while getting ready to put it all back together I found my 11 year old grandson goofing off with the jack. He had turned it upside down and also at some point had backed out the release valve. Now just when I need the jack it doesn't work. I figured it was air bound. I have tried opening the release valve and removing the oil filler plug then pumping a good amount of times then re-assembling over and over and still no lift. I also tried pulling up the saddle manualy and opening the releas valve while pushing the saddle down. Funny thing is with the release valve open and the oil filler plug out sometimes it will very slowly pump up with no weight on the saddle. Looking down the filler hole I can see the oil close to the top. Scratching my head on this one! Anybody have any suggestions?