For the record, this guy used sandpaper and polishing compounds (on a buffing wheel!) on his cover.
http://www.nappepin.com/predicta/predicta.htm
Sounds harsh to me. I guess he had deep scratches, which does not appear to be your problem.
I can testify that hand polishing with Novus won't do any harm. I used it on a little shallow boo-boo that the seller said had resulted from someone accidentally brushing it with a cigarette. A few years later, that spot, and the rest of the cover, look fine.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html