Air in jacks, check valves not set right, pistons not bottoming out or could be leveling speed in up is a little to slow if its a terminal floor.... I had this issue and confirmed all this was correct I added 1-1.5 gallon of the Maxton Max Gluide (helps with tight packings and is an additive for the oil) and problem went away... I was sceptical at first but now I am believer.