Well, I removed the couplate last night and I had to cut it up to remove it, since the access is very tight and a couple of the leads were bent. It's hard enough to remove one of those long, multiple-lead jobbies all in one piece when you have normal access.
As I recall, voltages on the 6CG7 were normal except the negative voltage on its grid was deficient or absent, similar to the HOT. Yesterday I did check that 6CG7 socket carefully, confirming that the resistance is normal on each pin and that every pin actually connects to the right spots. I also pushed things around and didn't see any evidence of an intermittent pin or broken trace.
I'm not confident that I can install a new couplate in this cramped space without messing up a trace underneath. Whether the TV will need further work at this stage is unknown. Adding quick disconnects on all of the board leads seems worth a try. Then I can swap the board in and out faster and less destructively. This local place has small Molex connectors:
http://shop.vetcosurplus.com/catalog...oducts_id=6845
I already connected three of the six ground stakes with a bus. If I complete the bus to connect all six of them, then I can use one Molex to connect the bus to a ground outside the board and perhaps reduce problems with bad board grounds.
Some of the leads from the board will need lengthening. I'm going to leave the existing wrapped/soldered connections alone and cut each lead an inch or so from the board to install the disconnect.
This will take a while. My hand-drawn diagram lists about three dozen leads, plus the six ground connections. After drawing that diagram, I got a copy of the Philco service manual, which has a nice diagram labeling everything on the board. I'll use their numbering scheme this time around.
Phil Nelson