Unfortunately, I can’t post photos right now because photobucket is all messed up for some reason … I will try to figure something out so you can see the current shade of black of the aluminum.
I used Windex on a soft rag and it took off a light coating of dirt and grime without affecting the lettering in the logo but had no effect on the color which is kinda' what I expected.
This is my guess … it sounds like when the aluminum is anodized they include a pigment in the bath to add color and I suspect that this fading is a type of lobster effect. It is not that the lobster turns red when you boil it; the red is always there, it is that other pigments chemically change (notice I didn’t say ‘go away’). Or at least that is my understanding of the color change in a lobster and probably something similar is happening here. This leads me to believe that there is probably not much I can do with the exception of a fairly serious polishing to remove surface layers. I will probably avoid a polishing because I want to keep the decorative logo intact.
I do have an Amazon gift card burning a hole in my pocket and when we moved a little over a year ago my supply of various chemicals (cleaners, adhesives, etc.) could not come with me so I will probably just order a can of the polishing “wadding” and try it on some other projects.