Well, the way I look at it is that you can't read the numbers now either, and it appeared you had pretty much given up on just trying to scrape the potting material out.
In my experience, a lot of chips have etched numbers that are not removed except by grinding. Printed numbers may or may not be damaged or removed, depending what was used to print them. Often, when a painted stencil is removed, there is a ghost image left that can still be read.
However, I think you misunderstand the whole process. Those solvents I mentioned will probably not dissolve the potting material. They may cause it to swell and become friable so that it can be more easily removed. It is a soak, scrape, soak, scrape type of process.
I picked those solvents because I thought you might have access to them. You might also consider soaking in one of the alkyl sulfonic acid based caulk removers. I recently used McKanica with good results on silicone caulk. McKanica is carried by Ace and is quite expensive for what it is (
https://en.wikipedia.org/wiki/Alkyl_sulfonic_acid). If you have access to sulfur trioxide, you could make your own by bubbling it through mineral spirits. In fact one of the other brands seems to be made that way. I can't remember that brand right now, except it was no cheaper. The Lowes stuff does not work. My first choice, though, would be to try the solvents/paint remover first.
As a last alternative, you might take it to the airport and see if TSA will help you see through the potting material. Be sure to have your attorney's cell phone number handy.
John