[Arran]

Mike;
  Those plastic encased paper caps, whether they be Black Beauties, or Bumble Bees, or Sangamo "Little Chiefs", are all troublesome regardless of how they test for value. They are the only caps I have encountered that will shoot their contents out of their lead holes when they get electrically leaky enough, I have heard in some cases they will build up enough pressure to explode like an electrolytic. In fact I have a Canadian Westinghouse model 501A that had pink Sangamo "Little Chief" caps are original factory equipment, and they are all bad, leaky or open circuit,  and oddly enough it is one of the few Canadian sets I don't have a diagram for.
  With regard to the resistor with the green oxidation, is it coated with a tan, sand like substance? If it is I would replace it, those are like the plastic shelled paper caps, they seemed like a good idea at the time, but turned out to be garbage over the long run, and Brand Z liked them as well in that era apparently. Those are so unreliable that I have found ones that were NOS, and never even used, that went that way, first they go up in resistance, then go open, even if they test sort of all right, they won't be for long.
Regards
Arran