Motor Maniac handy commutator cleaner
This thing is really cool and simple, it takes an existing product, like the comm cleaning stick and makes it better. If the comm cleaning stick is a bit of a pain to use or you don’t have a commutator lathe, then this thing is a great solution. It comes supplied with a handle to turn the commutator, and all you do is place the supplied grinding stone into the space where the brush on your motor goes and the supplied spring keeps the correct pressure on it, then you turn the handle and it grinds the end of the commutator.
Source: Ark Inc [ark-inc.jp]