Thanks for the info but I have tried alcohol with no luck. It did work on my old Super 7. I even carried the swabs in my fight box. This is some kind of stain, not fuel or dirt, and it has discolored the plastic. I hoping for Futaba to have an answer as I can't be the only person with this problem and I don't want to destroy the front of the case.

BTW It's the best radio I've ever owned.