About 90% of the time when I hit the key to start my bobcat it will lurch & jerk. Apparently the traction drive is trying to kick in. I can cycle the ignition on & off and get it to start as it should, with no movement. Sometimes it takes quite a few cycles to get that to happen though. Doesn't matter if the parking brake is on or off. Doesn't matter if the lap bar is up or down.