Brush Holder Test

Check that there is no continuity between the (+) brush holder "A" and (-) brush holder "B". If there is no continuity, replace the brush holder assembly.

Fig 1: Checking Brush Holder
Courtesy of KIA MOTORS AMERICA, INC.
Insert the brush "A" into the brush holder and bring the brush into contact with the commutator, then attach a spring scale "B" to the spring "C". Measure the spring tension at the moment the spring lifts off the brush.
Spring tension

13.7 ~ 19.6N (1.4 ~ 2.0 kg, 3.09 ~ 4.41lb)

Fig 2: Measuring Spring Tension
Courtesy of KIA MOTORS AMERICA, INC.
Pry back each brush spring "A" with a screwdriver, then position the brush "B" about halfway out of its holder and release the spring to hold it there.

Fig 3: Prying Back Brush Springs
Courtesy of KIA MOTORS AMERICA, INC.
Install the armature in the housing and install the brush holder. Next, pry back each brush spring again and push the brush down until it seats against the commutator, then release the spring against the end of the brush.
NOTE: To seat new brushes, slip a strip of #500 or #600 sandpaper, with the grit side up, between the commutator and each brush and smoothly rotate the armature. The contact surface of the brushes will be sanded to the same contour as the commutator.

Fig 4: Installing Armature & Brush Holder
Courtesy of KIA MOTORS AMERICA, INC.