I have a powerbuilt 2.5 ton floor jack from kragen that won't lift anymore because the little hydraulic nub you push down on with the lever doesn't return back up so I can pump again. When I take a screw driver and pull the nub back up, I pump the jack again and the nub stays down.

If I pull the jack straight up from the lift point, it hold pressure just fine and stays up all the way. And there is no leaking oil from what I can see. The jack is completely filled with oil too.

Any help would be appreciated on helping to get this jack working