Most treadmill problems are caused by the motor. If the motor isn't properly attached to the treadmill, the treadmill can move, but the motor won't run. Another common treadmill problem is that the belt is slipping because of lint and other debris that accumulated under the deck. If you experience this, check the power cord connection and make sure it is plugged in securely. If so, you may need to inspect the unit to see if there is any damage to the motor or the belt.