Check that holes in the two lift arms are equal distance from one of the ends. You may have them out of wack. You have a 50% chance of putting them on backwards from each other unless you mark them. That will cause one side to lift either higher or lower. If you measure the hole from the end of the arm, there is about a difference of an inch from being in the exact center of the arm. I marked mine with blue tape so I know which arm is a left or right. Hope this makes sense.