Brush spring

Measure the force of the brush spring using a spring pressure gauge.
Read the spring pressure gauge at the brush tip projection of 2 mm {0.08 in}.

Fig 1: Checking Brush Tip Projection Dimension

G11274128

Courtesy of MAZDA MOTORS CORP.

If not within specification, replace the brush spring.
Generator brush spring force

Standard: 4.1-5.3 N {0.42-0.54 kgf, 1.0-1.1 lbf}

Minimum: 1.7 N {0.17 kgf, 0.38 lbf}