This is the brushed aluminum faceplate of a 400-CX and has a blotchy look to it, I believe that it was in a smoke/nicotine household. Tried a couple of things, warm water & dish soap, Mothers chrome cleaner, and diluted Super Clean. No improvement. I am staying away from any ammonia-based products as they are not good on aluminum, and the lettering is damn near perfect on this piece so I don't want to screw that up! Anyone had any positive experience with cleaning these types of faceplates? Looked all over the web with a million and one suggestions, some were people blowing it out of their butts, so for those who have had good luck with this, please let me know your process, thanks!