Probly the o rings. That's about all that is in there. Might just be dirty. Easy to take apart and clean. I fixed a Harbor freight jack that had a piston sticking by doing that.
No. I rarely used the thing but had a little job to do. Pushed the button and it made this odd sound. So was gonna put in some new batteries and surprise olde ones were leaking. Put in new ones and it worked fine. That was a couple weeks ago.