There was a piece broken out of the edge of the knob. Considering
the age of this radio from the early 60's, I decided to try to repair
it.
I made a little form to follow along the inner curve of the knob with
tape. A small bit of 5-minute epoxy was built up in this area and
allowed to harden over night.
I removed the tape, and sanded the outer curve and edge of the knob to
match. Using a Dremel tool with a cut-off disc and a jewelers file, I
replicated the grooves in the outer surface. After cleaning, it's now
ready for a little touch up color to match, once I get that mixed.
Dave WB4IUY