Section 8 (Starting System & Charging System (H4DO)): Generator: Inspection: Brush

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Measure the length of each brush. Replace the brush if wear exceeds service limits. There is a service limit mark (A) on each brush.
Brush length:

Standard (1)

18.5 mm (0.728 in)

Limit (2)

5.0 mm (0.197 in)

Fig 1: Identifying Brush Length Dimension
Courtesy of SUBARU OF AMERICA, INC.
Check that there is appropriate pressure on the brush spring. Using a spring pressure indicator, push the brush into the brush holder until its tip protrudes 2 mm (0.0787 in). Then measure the pressure of brush spring. If the pressure is 1.7 N (173 gf, 6.11 ozf) or less, replace the brush spring. 4.1 - 5.3 N (418 - 540 gf, 14.75 - 19.06 ozf) pressure is required on the new spring.

Fig 2: Measuring Pressure Of Brush Spring Using Spring Pressure Indicator
Courtesy of SUBARU OF AMERICA, INC.