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Thanks Tom and and guys.
I tried zeno's suggestion of pulling the 2IF tube, and...it doesn't have any visible effect at all.
I've re-checked M4 and it does ohm out as it should. I don't have a replacement readily available so I guess it's time to take apart another set and pull one out. This relates back to the other half of the problem, I have nearly a dozen non-working TVs here, none of them are useful to check the IF frequency (which is coming from a Philips 5509 btw, the 1077 is...not working yet). Since the (er, a) problem seems to be between V2 and the grid of V3A, I checked continuity of all the coils along the way, checked to make sure C22 isn't shorted, and verified the resistance of L7 and L6. Nothing off. I re-checked the resistance for V1 and V2 against the Sams and it's all as it should be.
One thing that't curious is the high plate voltage on those IF tubes. The main B+ at the choke is only 5V high, and the big dropper resistor is a little bit low but not much. It's weird to see that voltage way up there, like the tube isn't conducting at all.
At this point I don't know where else to go aside from the diode, and haven't checked the new IF tubes. That's first on the list for tomorrow, followed by changing out M4, and then maybe subbing a tuner somehow if I can find one that works.
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