That looks like it spent its life in a coal-fired factory. Here's a photo showing the Model 42 tuner
before it was cleaned.
I have an untouched AK Model 30 chassis sitting behind me, and the variable condensers look just as shiny as these.
I just posted an album of photos of the Model 42 restoration. You don't want to miss the definitive guide to restoration of Model 42 ball feet!
https://picasaweb.google.com/coldrb/...eat=directlink