Something I've done in sync errors. If the packings are dry. Clean the top foot or do of the pistons. Sand if necessary to get the area where the packings land cleaned and polished. Sometimes you may need to put some oil on the piston to clean it. Pull your springs and manual lower the jack's until they bottom out.
Another thing is every hyro I have, I put a quart of caterpiller 1U931 oil additive in the system. I've stopped sync errors with the "cat juice" itself.
Also see if you are running veggie oil, that will sometimes lose viscosity and get gummy.