Bench Testing: Brushes

Measure the length of each brush. See Fig 1 . If wear exceeds the service limit, replace the brush. Each has the service limit mark (A) on it.
Checking brush for proper pressure using a spring pressure indicator, push the brush into the brush holder until its tip protrudes .08" (2 mm). See Fig 2 . Then measure the pressure of brush spring.

Fig 1: Measuring Brush Length

Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Checking Brush Spring Pressure

Courtesy of SUBARU OF AMERICA, INC.