I looked through the old photos of my T-67 restoration, and I don't have one that shows the underside of the 1B3GT socket. I might be wrong, but I believe I have seen those sockets with and without corona rings. It's hard to imagine someone removing that part, so my guess is that yours never had a ring.
The following photo shows my 1B3GT from above, with a roll of something like fish paper covering the top cap.
The T-67 is a decent performer when restored, so I'd encourage you to get yours running. Here are some restoration notes about mine:
https://antiqueradio.org/hallit-67.htm
Regards,
Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html
