I recently bought a TA-15 with a tarnished top panel. Through a process of unexpected results I came to a solution (and, yes, I'm using the word "solution as it ought to be used; a solution addresses a problem - it's not a product [like an email "solution"] or a service!!! 
).
My first idea was to see if I could use polish. That didn't work; it made what should be a satin finish shiny and didn’t do anything to the tarnish. Next I tried very fine, 2000 grit, sandpaper, the wet/dry stuff used in body shops. That just made everything dull where I tried it. I then tried a polishing tool and some polish. That left it looking smeared, and (!) I noticed when looking at an angle that I'd dug small groves into the panel. Ouch!
That turned out to be just what I needed, though, because taking a more aggressive grit sandpaper to it to try and deal with the groves ended up finally getting through all the finish Mesa had used and took me to the bare aluminum I'd started hoping I'd find.
I put the panel into a vice, protecting it from getting scratched, and went at it with an orbital sander with 80 (I think) grit disks. I love how it turned out and wanted to share this as an option that doesn’t cost a thing except some time if you've got the tools.
).My first idea was to see if I could use polish. That didn't work; it made what should be a satin finish shiny and didn’t do anything to the tarnish. Next I tried very fine, 2000 grit, sandpaper, the wet/dry stuff used in body shops. That just made everything dull where I tried it. I then tried a polishing tool and some polish. That left it looking smeared, and (!) I noticed when looking at an angle that I'd dug small groves into the panel. Ouch!
That turned out to be just what I needed, though, because taking a more aggressive grit sandpaper to it to try and deal with the groves ended up finally getting through all the finish Mesa had used and took me to the bare aluminum I'd started hoping I'd find.
I put the panel into a vice, protecting it from getting scratched, and went at it with an orbital sander with 80 (I think) grit disks. I love how it turned out and wanted to share this as an option that doesn’t cost a thing except some time if you've got the tools.
