[astravision]

You could try some T-Cut and a little elbow grease on your opaque tuning knob, I have done this to an E.A.R portable radiogram and it did the trick well. If yours is really bad you could start with some 1000 grade wet and dry and gently remove the oxidation remembering to use plenty of water on the paper. Then dry off and use the T-Cut.

Your restoration is looking really good, all the best with it