The different rectified DC voltages are from different tubes, 427VDC with a 6L6 plugged in, 435 VDC with a 6V6 plugged in. Sorry, forgot to mention that. Also, yes, two 100ohm resistors are attached to ground for an artificial center tap.

Ok, so I used a different meter and got 5.5 VAC on pin 2 and 3.2 VAC on pin 8. Why on earth my other meter (a new Klein Tool MM400 auto ranging) reads 0 VAC on the rectifier filaments but reads exactly the same on the other filaments as my other meter (3.4 VAC, BK Toolkit 2704B manual ranging) is baffling to me. Anyway, those readings on pin 2 and 8 are too high, they should be 2.5 VAC each, correct? Could that be due to the higher primary too?

Back to the meters. Why would the Klein meter detect VAC at one point, but not at another point where a different is able to detect VAC? The voltages aren’t even supposed to be that different. The meters are shown below.