Brush Holder
Connect a test lamp between brushes. Lamp should NOT light. Connect test lamp between "DF" terminal and "+" brush. Lamp should give steady light even if brush and/or terminal cable is moved. Connect test lamp between 2-5 watt test lamp between stator plates and a terminal on stator. If lamp lights, isolation between stator winding and stator plates is defective and stator should be replaced.
NOTE:
Brush length is measured between brush contact surface and holder, with brush resting against spring.