Can't get N72 to pass signal

[Whoopysnorp]

I'm having difficulty getting an N72 to work. This is my first SCA kit build.

Q1 through Q3 are all measuring within .2 volts of what the table says they should. Q4 measures about 6v on the collector, which is about a volt higher than prescribed. Base and emitter are at .8v and .2v respectively. Q5 shows 22.4v on the collector, 6.2v on the base, and 5.7v on the emitter. Q6 is 22.4v collector, 4.4 base, 3.8 emitter. When I adjusted R39 for 22.2v on Q6, I had 4.4v at R40. Readjusting R39 for 3.75v at R40 resulted in .2v more at the Q6 collector. Otherwise, it seems like power is getting to where it's supposed to.

I tried following a signal from a tone generator with a signal probe, and the thing that's stumping me is that it doesn't seem to be getting out of the input transformer. Continuity between the transformer pins and the PCB seems fine, but it seems like I ought to detect some kind of signal coming out of pin 7 of the transformer, and I don't. Any tips on how to troubleshoot the I/O?

One additional note about this build: when I first finished it, it calibrated fine, then I put the chassis in my rack to try to use it, and found that it didn't pass signal. When I got it back on the bench, I found that I was no longer able to get the Q6 collector to measure correctly, and I eventually traced that to a dead short in R40. I replaced the part and was able to get everything calibrated again. I'm including this detail in case it's a clue about anything.

P.S. I recently noticed the precaution about not letting the Q6 heat sink come into contact with the chassis. As far as I can tell, that heat sink doesn't conduct electricity. Is that warning still applicable to the latest revision?

[Whoopysnorp]

Whatever is going on has something to do with the input transformer. On one of my A12Bs, I can supply a test tone to the input and use an audio probe on the transformer output to detect my signal there, stepped up in amplitude compared to its input level, just as you would expect. On the N72, my audio probe detects nothing at pin 7. I removed the transformer from the circuit and measured the DC resistance on the coils; the primaries each measure about 25 ohms, which is about one ohm higher than specced, and the secondaries each measure about 144 ohms, which is about 14 ohms higher than specced. Is this a concern? When I put it back in the circuit I'm measuring 270 ohms between pins 7 and 10, which is closer to what I would expect. There are no shorts between any of the coils and ground. When in the circuit, I show 270 ohms between the non-grounded leg of C1 and ground, which makes perfect sense. So if the resistances on the transformer measure OK, why am I not getting anything out from it?