Brian, most of the time I won't buy anything with ID/SS number on it,... anywhere.
I go through a lot of stuff, and it's been my experience that 99.9% of buyers don't want, or flatly won't buy disfigured items.
About the only time I do, is when I have a faceplate, etc., to replace the trashed one.
If you watch Ebay, pieces that have ID number etched/engraved, sell for less.
Vintage pieces of equipment are rapidly becoming "collectible"
As such, anything that is defaced, isn't a desirable piece to own.
That's what my buyers are telling me anyway.