If you follow some links in the OP you can end up at a source article[1] that has some comments on the actual chemical processes occurring for both the discolou

If you follow some links in the OP you can end up at a source article[1] that has some comments on the actual chemical processes occurring for both the discolouration and reversal (Ctrl-F "bromine"). TL;DR: Over time the bromine based flame retardants in retro-era plastics degrade (hence the yellow/brown colour) and H2O2 plus some energy (UV light/heat) can be used to reverse the process. [1] http://www.vintagecomputing.com/index.php/archives/189 http://www.vintagecomputing.com/index.php/archives/189