ok well my motor started smoking from the comm area. it still runs but it got reaaaallly hot. my GTX is ok but it was right next to the endbell and i think it might have gotten hot as well. im wondering if the motor will be ok if i cut the comm and change the brushes.
I had a similar thing happen. Not much to risk in cutting the comm and throwing in some new brushes. For me, it didn't work out. The darkened windings must have developed a short, as it continued to generate too much heat and not enough power.