I know this is a very old thread, but it's the best I've found for pictures of the original knobs. I'm working on a 42-KR3 for a friend and it's missing the knobs. It's doubtful that I'll be able to find the originals, so my plan is to design and print them on my 3D printer. They won't look as nice as the originals, but should look ok if I can get the shape and dimensions right. Any chance I can get you to take some good detailed photos of those original knobs, as well as some accurate dimensions?
Rich, you might want to contact these people. They seem to have pared down their website. One used to be able to look through pages that showed the knobs they had in stock. Contact them anyway, they have molds and make the knobs. http://www.antiqueradioknobs.com/
You won't get an answer, Larry Bordonaro sadly passed away several years ago. I'm frankly surprised his site is still up.
Ed Schutz (renovatedradios) took over much of Larry's old product line, but not all.
Edit: The knobs are the same as used on many of the very small Transitone/Philco Transitone radios as well as some slightly larger Philco table models (40-120 comes to mind), only painted to match the cabinet.