Tom,
The trim is SOLID brass. It is not plated copper. Brass is acutally COPPER, that is alloyed with zinc. The copper pits or spots you see in the brass finish are areas where the zinc has likely been depleatd from years of chemical corrosion. When that happens the base metal COPPER is what is left and it looks like it was brass plated copper. I can asure you that the trim is solid brass and you can steel wool and scotch brite until you are blue in the face and you will never wear through the plating because it is not plated, it is solid brass. For an easy way to polish solid brass trim follow this link to my web site.
http://antiquetvguy.com/Web%20Pages/...finishing.html
Good Luck,
Bob