Thanks Mark. It was the gear wheel on the potentiometer slipping so I adjusted it and tightened the set screws. I also noticed that the nut that holds the pot switch was loose also so that is fixed as well. That is the only problem I have had so far and the machine is almost never off when I am home. So far I have built an adjustable height welding table with rotating top,a plow for an atv, and a plow and mount and wheel weights for my garden tractor as well as fixing the rear strut mount on a car. This is a very versatile unit