Hey Berridale, Just a hint, if you wish clean up the commutator it should NEVER be cleaned with Emery or ANY abrasive like product. (Sand Paper/Wet & Dry/Emery no matter how fine)
The Proper way is on a Lathe, and as most of us don't have one, (like me) the next best way is using a SOFT Pencil Eraser to remove any Carbon build up & then Isopropyl Alcohol. Don't be concerned about getting it bright & coppery, as most of the dark marking is just heat discolouration.
Using abrasives causes excessive & uneven wear on the Comm, tears apart the surface with micro scoring, and last but not least, causes particals to become embedded in the surface. All of this resulting in excessive & exacerbated wear of the comm & brushes.
But you are 100% spot on with everything else you say.
I myself bought my "Ruby", only because she was being sold for an unbelievable price due to the accumulator being faulty, a simple screw off / screw on fix. 2 days later I bought an entire 156 less engine for $50, as my own personal lifetime of spares.
Those were the best $50 I have ever spent, saved me $100s of dollars in spares.