When debugging a Williams Gorgar sound(no sound out at all), I discovered that the voltage coming from the transformer at that tap is ~9.4V. According to the schematics I have, that should be 18.7V AC. So, I'm assuming that this is likely the root cause of my problem.
Since the rest of the system seems to power up just fine, I'm inclined to simply replace this particular voltage, with a separate AC transformer. Has anyone else tried this?