I have a lift that starts to surge/shutter, slow down it seems after 20-30minutes of opperation with no codes. If you try to keep going, it even go backwards a few inches during its surge even with accelarator in full forward. It just tries to jerk foward and backwards. I released the brake by installing the brake release screws to verify its not the brake dragging with no change. Hard plugging seems to make it act up sooner. I tried to get into maintenance mode to run any kind of test or to calibrate or even learn but will not get me into those areas.
Any help would be appriciated....