Since others were interested in this thread, I thought I'd post a reply 
from David Yates. In another note he mentioned that his dad uses 
Jeweler's Rouge to remove small scratches in glass...and suggests 
checking with local jewelers as a possibly supply source.

> Joe, ordinary rubbing/cutting compound will NOT do, it simply isn't
> hard enough.  Jeweller's rouge is the way to go.  It is used for
> polishing gemstones.
> regards from downunder.
> David Yates

Thanks for the response, David! 8) Joe ('71 campmobile -- "AquaVan")