Hi Paul-
I swapped tubes and everything stayed the same except for a rarified minute 17/B2 were reading 90V! Then they went back to 72V. I checked the R1 resistors and they are correct. I have re-soldered all the wires and posts that connect to the C4S board and the 5 lug strip, and I sill get 72V. I almost have it, it appears. Terminals 11 through 15 on the first 5 lug strip all read correct voltages. On the other 5 lug strip I get 16 (5V), 17 (72V), 18 (OV), 19 (9.87), and 20 (6.2mV). Must be a bad joint somewhere.
Thanks, Michael