[KCMike]

Yes the switches are off./unmuted. I have tried pushing the switches in and out with it playing. Still low volume. The loudness button does function on AM. Can't really tell on FM.
I have the mode selector in normal stereo setting.
I do have to ask if you know why the base of the transistors on the control board make a loud hum through the speakers when only being touched with the tip of one probe of a DMM? I don't see how you could ever check voltages on the transistors with this condition.
I did check all the B+ voltages to all the boards and they are very close to, or are correct.
I think Ron might be right that its in the FM IF. section or the MPX. I have not messed with or turned any adjustments in regard to FM/tuner/ or AM boards. I do know better than to mess with any of them.