this is an amazing discovery ;)
background: I bought a very old (1960's or 70's, roughly) power supply from ebay, in need of rejuvenation.
look at the two red knobs, top group and bottom group. both knobs were removed from the device, very thoroughly cleaned with hot water, soap and a sponge, then air dried. I was hoping that simply cleaning the knobs would be enough. it wasn't.
so, how did I get the top knob pair to be so nice and shiny?
triple antibiotic ointment!
the stuff that comes out of a small tube that you use on skin cuts before you put a bandage on ;) it has a vaseline like base and this appears to bond (?) to the plastic or somehow refresh it.
its good for when your hands are dry; but apparently its also good for when your 40 year old knobs are dry, too! LOL
just wipe on, let set for a minute or so, then wipe off.
and a side benefit: if you ever cut or burn yourself in the lab, just grab for the nearest voltage- or current-adjust knob ;)
interior shot, with non-printed circuit board: www.flickr.com/photos/linux-works/6932196670/in/photostream