Check ebay frequently sometimes you can find a brushed motor com cutter. Hobbyking.com has a decent brush cutter for pretty cheap. As for breaking in brushed motors we used to break em in in a mix of water, coke a cola, WD40, simple green, and tooth paste. It polished the com and broke in the brushes pretty well. Just had to clean em out with motor cleaner and repel the bearings afterwards. We used mouse milk machine oil and I gotta tell ya that stuff is AMAZING as bearing oil!!!!!