Was reading up on treadmill motor diagnostics and thought I'd toss something out for discussion. NordicTrack make a habit of checking if the motor runs at high and low speed, which makes sense as motors that will run at a low rpm may not do as well at high rpm and vice versa. Fans is also often checked for treadmill motors as overheating issue are typically the result of either the fan not spinning or spinning but not moving air. The controller board is also another common issue for treadmills; the motor is often assumed as the problem rather than checking the controller board to make sure its functioning proper.