How is the seating the brushes on a DC motor commutator first accomplished?

Correct Answer: Option D — using fine sandpaper on a deenergized machine between the brush and the commutator to establish the proper curvature

Initial brush contouring requires placing fine sandpaper abrasive-side down against the commutator on a de-energized machine, pulling it strictly in the direction of rotation. This establishes precise mechanical curvature, ensuring full-face contact and preventing destructive sparking during operation.