Brush And Brush Holder

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.

Visually check the brush. If there is any abnormal wear or cracks, replace the brush.
Measure the length of the brush. If it exceeds service limits, replace the brush.
Brush length:

Standard

12.3 mm (0.484 in)

Limit

7.0 mm (0.276 in)

Fig 1: Identifying Brush With Its Service Limit Line
Courtesy of SUBARU OF AMERICA, INC.
Check that the brush moves smoothly in the brush holder.
Measure the brush spring force with a spring scale. Replace the brush holder if below the service limit.
Brush spring force:

Standard

15.9 - 19.5 N (1.62 - 1.99 kgf, 3.57 - 4.38 lbf) (When new)

Limit

2.5 N (0.25 kgf, 0.56 lbf)