This is a much simpler modification. I've been buying a lot of older test equipment recently for the new company and I like to have things looking their best. Aging plastics can discolour and one solution to un-beige your gear is Retr0Brite. In Vancouver (Canada), a good place to get concentrated H2O2 is Finlandia Natural Pharmacy & Health Centre on Broadway. They sell 29% solutions in 1l size bottles - and it works!
I didn't use a UV lamp, just cheap washing powder and natural sunlight.
Here's the back end of two Fluke 2190a boxes, both were pretty much the same colour before treatment, the upper one had three rounds with the Retr0Brite, the bottom one has not been treated.