When this unit is lifting and main lift tops out it is a hard transition. (Big bounce). It will only do it in the first stage to the second stage. After that it is nice and smooth going up. When you come down when the second stage comes to its resting area there is a hard bounce in the carriage and then it's smooth all the way down. When you compare it to another Toyota the transion is nice and smooth. Seamless in all stages. We have removed the main lift cylinder and it looks good. Repacked it and installed new valve on bottom of ram. We have hooked hydraulics up from another unit and tested it. We even swapped the blocks and the check valves out from another unit, and still the same problem. The problem is in the upright or we are missing something in a cylinder. The upright doesn't hang up. The rails are even. Does anybody have any ideas?