Not sure exactly what your jacks problems are, but I had one that was severely binding. I had always meant to do the lubrication maintenance but put it off. It got so bad that I really had to do some work to it. I documented it towards the end of the thread linked below
There was this great write up by member KKELLER14K some time ago of which I copied and printed for my use when I would get around to the maintenance. See article here:
Happijac lubrication Unfortunately the photo images were lost because of that photovucket snafu. I have a copy in PDF format if you want me to send to to you... perhaps it is just the normal maintenance that need to be performed.
And... to anyone else that would like a copy of the PDF of the procedure, please PM me and I will forward it out.