My OEM brushes lasted around 70,000 miles, before needing replacement.
I got the dimly glowing charge light, as the 'snail' type springs could not push down on the brushes, to keep them in good contact with the slip rings.
Until replacement brushes arrived, I cut a couple of small pieces of a Plexiglas material, and pulled up on the springs to clear the brushes, and installed the plastic on top of the brushes, then let the springs back down, dim charge light went away .