Brush Holder
Connect a test lamp between the brushes. Lamp should not light. Next connect test lamp between "DF" terminal and the "+" brush. Lamp should give steady light even if brush or terminal cable is moved (see Fig 1). Connect test lamp between brush holder frame and "-" brush. Lamp should give steady light. If test results are not satisfactory or brush length is less than 3/16" (5 mm), replace brush holder.
NOTE:
Brush length is measured between brush contact surface and holder, with brush resting against spring.