Sunrise, my experience with the bild a motors I see that the Lionel classics(90's)through the early 2000 motors seem to be the best running, I have had some newer Lionel corp stuff that just runs horrible, or arch really bad don't know why but all Mth tinplate traditions stuff runs like a clock, as for the brushes, I have learned it doesn't hurt to do a maintaince check around every 40 hours of run time and maybe a light oil check every week, hope this helps, but I have all traditional motors except for one proto 1 400e that's runs super to this day.
Ken