"As the armature rotates, a pair of brushes connects one end of a specific armature coil to power and the other end to ground."

The brushes on my starter look brand new; but are however, quite thick, and I believe, they overlap a couple bars at all times. This makes me wonder, is it possible the previous owner tried to rebuild the starter and put on an incorrect brush set? Is that possible? What is the correct width, or thickness of the original brushes?

-Matt