The turnout from our driveway has enough of a slope that I ran the front tires up on (3) 2x10 planks under each wheel. Then I autoextended the HWH jacks, expecting the fronts to land on the 2.5" thick boards under the jacks. Didn't. Checked level with bubble level on counter--perfect!!! Bubble is dead center. Could I have caused damage to front jacks? Leveling system stopped automatically. No leakage. I was really trying to eliminate "rocking". Rear jacks are down on 1.5" thick plywood pads.