I should clean house more often. I was rummaging through junk boxes and found these:
The cases are identical to the original, although the legs are a little thinner and closer together. The original has the codes 1107330 -1 4-54. These are stamped ED and have codes 1107863 -3 3-66 and 1107863 -1 4-77. If the last three digits are date codes, then maybe I have one from each decade.
I'll bend/thicken the legs on one of them and try it out.
I'm going to build the video preamp described in the 1956
RCA Broadcast News article so that I can bypass the front end. If the problem disappears, that tells us it was located upstream, I guess.
I also ordered some 100% DeOxit and leetle brushes to see whether cleaning the front-end sockets helps.
Phil Nelson