17. You'll typically find that that the faces of the clutch plates are badly worn over time. As they wear they begin to slip more and you gradually lose the differential lock effect and the axle behaves more like a simple open differential. On these units, the cupped spring plate eventually fatigues and breaks apart as the one shown here has done. These pieces may work their way out of the carrier and can cause nasty damage to the gear surfaces. Fortunately, in our case, the couple of loose pieces fell harmlessly to the bottom of the housing.