Brushes & Springs Test

Use vernier calipers to check brush length. See Fig 1. If length is less than specification, replace brush holder and field frame. See STARTER SPECIFICATIONS . If brushes are okay, go to step 2.
Check brush spring load using a spring scale. See Fig 2. Pull the scale and take reading when spring separates from the brush. If the spring load is less than specification, replace the springs. See STARTER SPECIFICATIONS .
Using an ohmmeter, check that there is no continuity between the positive and negative brush holders. See Fig 1.

Fig 1: Measuring Brush Length & Testing Brush Holder Continuity

Fig 2: Performing Brush Spring Load Test