Paul, the black plastic thing on the 9 pin socket is a "socket saver". It's got gold plated connectors and is easier to roll tubes with (they tend to insert/remove more easily). The voltage measurements below were taken with that socket saver in place.
You are also correct, the 9 pin tube is glowing. Picture below.
I re-inspected B7 and B8, and all the socket connections. They all seem fine; I can see solder on them all, and none of the wires are loose. But I found other problems...
After spending some time pondering my work, I have discovered a couple more mistakes:
6L was unsoldered
Red wire at 13U was unsoldered
So I resoldered those joints, and resoldered several other questionable joints: 10L, 12L, 13L, and 15L.
Voltage and resistance checks below. After powering on, I note both tubes glowing, pictures below.
Resistance
Terminal = Reading
1 = 30k and rising
2 = 4k and rising
3 = 0 ohms
4 = 5k and rising
5 = 50k
6 = 0 ohms
7 = 3k ohms
8 = 0 ohms
9 = 3k ohms
10 = 0 ohms
12 = 0 ohms
13 = 5k ohms and rising
14 = 0 ohms
20 = 0 ohms
22 = 0 ohms
B3 = 3k ohms
B6 = 3k ohms
RCA centers = 100k - 200k ohms
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Voltages
Terminal = VDC
1 = 80v
2 = 190v
3 = 0v
4 = 190v
5 = 85v
6 = 0v
7 = 115v
8 = 0v
9 = 115v
10 = 0v
Thank you once again for your help! Really appreciate it.