Jaysin, that is an excellent question, one that I don't believe has been posed before.
This is how I clean mine.
When I give the tray that it is mounted in a "good" cleaning; I wipe all of the dust off with a dry paper towel.
Then, I'll give the whole thing (tray and all) a good washing down with Rubbing alcohol, using paper towels.
That's what works for me.