If you encounter problems with your Craftsman 50239 floor jack, there could be a number of reasons for the problems. There could be air in the jack's hydraulics, the jack's moving parts could need oil, the oil currently in the jack may be too old or the release valve may not be closed tightly enough. Fortunately, you can solve each problem on your own without having to get the jack professionally repaired.
Turn the jack's handle clockwise to tightly close the release valve. If the release valve is not tightly closed, the jack does not support weight properly, which means it may start to lower after lifting or, in extreme cases, not lift at all.
Reduce the weight on the jack. If the jack is overloaded, it does not lift properly (if it lifts at all).
Add lubricating oil to the jack's moving parts. If the jack's moving parts are not properly lubricated, the jack can lock up.
Replace the oil inside the jack, as old oil can hinder performance. Remove the tool tray (located at the base of the jack, in front of the handle), then unscrew the oil filler screw. Turn the jack's handle counterclockwise to open the release valve, then turn the jack over and dump the oil out through the oil filler hole and into an appropriate container. Turn the jack back over and pour in the fresh oil. Rapidly pump the jack's handle (with the release valve still open) to release air from the hydraulic system, then screw the oil filler screw back in and put the tool tray back in to place.
Remove air from the hydraulic system. Remove the jack's tool tray and unscrew the oil filler screw. Turn the jack's handle counterclockwise to open the release valve, then rapidly pump the jack's handle. Reinsert both the oil filler screw and the tool tray.
