Thank you! I think I'll stick with a general cleaning of the shell. They are 52 years old, so the fade gives it some character.Not much you can do. The outer layer on a sparkle is tinted to the color you see (the sparkles inside are silver) and this layer can yellow or cloud when exposed to too much UV light. You can try wet sanding the very top of the wrap with ultra fine grit sandpaper. If the clouding is just in the very top of that layer of the wrap you might be able to remove it. Some people have had luck with this method but generally that is when tried on pearl finishes like White Marine Pearl which are a bit different in makeup. The risk is that you could easily sand through the thin outer layer, possibly removing the color (giving you a spot of silver sparkle) or even go though entirely down to the sparkle layer. So it's a possible option, but not one to take lightly.
I have a blue sparkle set that is pretty immaculate. I bought a 14x14 floor tom to add on and it is yellowed a bit and looks duller than the rest of the set. I experimented a bit on that drum with no luck from polishing. I did not try wet sanding though. My guess is I'm actually the only one who notices the difference when set up so I've decided to just live with it.