Re: Spot re-lacquer
Since all you want to do is curb any discoloring or degradation from skin oil etc. on the newly exposed bare brass spots, I'd just shoot them with a thin coat of touch up lacquerer available from
www.ferreestools.com. This is clear lacquer, not gold dyed, so a color match isn't going to take place( they do offer several shades of the latter, but these requite that you shoot them out of a paint sprayer), but it will give an air/water tight seal.
Should you have the idea of using an automotive lacquer, don't. These are formulated to spray a much too think coat, and can make a mess for such a small touch up.
For a quick fix, a thin spraying clear gloss finish such as a Hobby clear coat lacquer spray finish like those made by Testors, Floquil and Humbrol (not the enamel ones!) will work in a pinch.