The PHILCO Phorum

I recently acquired a Philco 40-216 with remote control. The cabinet has a hole about 3/8" in diameter in the center of the cabinet right below the fold-up cover. I looked at other similar sets such as a 39-45, 41-316, and 39-116 in various galleries and they ALL seem to have the same hole. It looks like something is MISSING. But WHAT? And why do ALL sets I have seen have this hole?

Does anyone know what might be missing and have a photo?

Thanks

Very simply, a pilot light. There was a plastic jewel that went in there. I use to have a 42-1015. I used to be able to get red jewels from when I was in the vending business years ago. It was for a "use coin only" light. I used the little piece from the top of a red Bic pen in some cases now. It's not transparent like the originals but works. The originals disintegrated and turned to powder which is why they are always missing.