Your treadmill should be level for optimum use. Once you have placed your treadmill where you intend to use it, raise or lower one or both of the adjustable levelers located on the bottom of the treadmill frame. A carpenter’s level is recommended. If your treadmill is not level, the running belt may not track properly. Once you have leveled your treadmill, lock the levelers in place by tightening the nuts against the frame.