When you said that the conductors are connected to a "board" I assumed you meant the terminal area of the key. Now I see that you meant the wafers that allow the assembly process to go more quickly.
"I hear tones, they sound correct, but CBDT and this only happens on the 4 lines, intercom line work fine."
So, the dial generates the correct tones, and the intercom operates correctly. In the old days, the DTMF receivers in a CO were much more forgiving to frequency variations than the cheap(er) receivers in a local intercom. Nowadays, I'm not sure about the ATA's.
You hear tones when on a CO line, but you CBDT. The next thing to do is to put two sets on the same cable, press the same CO key on both, press the same TT button on both, and listen for a "beat." The suspect dial may be just a little off frequency. The adjusting slugs on the back of the dial can fix that.
Other than that, I guess 52 years of experience is not enough. I'm stumped.
