What's it not doing ?
They are not at all complicated , as already mentioned it could be an easy tweak that may get it going again. I bought a good sized asian floor jack at least ten years ago , it has had issues that I was able to overcome without difficulty.
On a similar topic , I have a very old hydraulic motorcycle lift bench , I think it was made overseas , maybe not asia , possibly italy . It's old and has been used commercially , About seven years ago I decided to restore it , repaint , rebuild the hydraulics , freshen it up , it leaked oil pretty bad . There are similar bike lifts still available , the units sold at pricess auto are an asian copy of the lift I have . I ordered a seal / overhaul kit to rebuild the hydraulics from one of my suppliers , after all it looked the same
. I disassembled the entire lift , repainted all the pieces and started to rebuild the ram & foot pump mechanism only to find that the main seal for the piston wasn't even close to what was needed ! My solution was to make a new piston , changing the design so that I could use the seal that was in the rebuild kit , it worked well and is still in use with no leaks .
Try fixing it yourself .
I've seen new hydraulic units that were low on oil right out of the box.