Retrobright - COOL! Thanks for the reference. Very interesting to read their work on the causes of the yellowing. I'd assumed it was due to UV-induced breakdown of the ABS plastic chains. But no....
Sanding is not an option since the surface has a fine texture, that I don't want to damage. Even just rubbing hard with a solvent-wet tissue to remove old sticker residue tends to 'shine' the surface in patches. The number of things I've put aside, waiting till I get around to setting up my big compressor and grit-blasting cabinet, grows.