Yes, you want to break in a brushed motor to seat the brushes fully. I used to use a fan mounted to the armature and run the motor at 3volts for about 5 minutes with a couple drops of comm drops to do this. After this I would spray out the comm and reoil the bushings, but do not remove the brushes while doing this you want the brush to stay where it's at. If you change/remove the brushes or clean/cut the comm you will need to repeat the breakin procedure.