Bill,
?Commutators once were made differently. Most in the last 25 years or more are injection molded, and have sub-flush mica. This was so that they didn't need to be under-cut when manufactured. They were trued using a diamond bit, spinning at 2000+ RPM. If you attempt to face/true, you quite likely will smear the copper into the slots, instead of actually cutting it. Copper is too soft to satisfactorily machine on an interrupted surface. In the old days, one might just cut down to the mica and undercut anew. Loses comm life, but saves time. Unless it is badly grooved, polish with 200-240 grit aluminum oxide. (don't use emery cloth). Light grooves, irregularities can be polished out. If the brush track is significantly lower than the rest of the bar(s), it will need to be turned. Then you will need to use the ground hacksaw blade or an X-Acto knife to clean the slots. Then it should go on a growler to check for shorts between the slots.
Post a before pic...
Brush caps and brushes (which you already have) Arrowhead Electric. ? Here is their brusholder/cap page:
Here is their main page:
Jeff in Lone Star, TX
