[Hallicrafters] SX-101 MK III Main Tuning Dial

[Steven Stroschein]

Hoping someone out there can help me. The main tuning knob skirt on a '101 MK III I recently acquired almost looks as though it was plated in brass. I've had a few through the years & none were like this. I'd like to clean it, but I don't want to damage it in the process. I initially thought it might be a result of smoke damage, but the rest of the radio doesn't show any.
   
  Any ideas as to what I could do/use?
   
  Thanks & 73,
   
  Steve 
  W9XF