Hi there.  New member.  I have a 1936 teaching Corona that appears to be in great working order (at least there’s nothing amiss with it that I know of) but I’d like to know what I can do to preserve the colors on the keys, which still look pretty good to my eye.  I keep it in a dark place separate from the case because the typewriter smells good, the case not so much.  I doubt there’s much more I can do, but doesn’t hurt to ask.  I won’t bore anyone with basic maintenance questions, I’m sure there’s plenty of info here, but if anyone knows another reputable all-in-one reference that would be very much appreciated.