I have a couple of SkyTrak 6036's of varying age. They each occasionally have an issue with not moving when placed in gear. The park brake is off and the electrical to the valves is fine. You can place in gear and wait for a bit then they will usually start moving. I have changed the transmission fluid and filters and checked to be sure there was no trash making a valve stick. Has anyone else had this problem and figured it out, we have had mechanics look at them but to no avail, said everything was fine.