seeburg Q shfa2 amp problem

Hi all:
We have recapped the SHFA2 in our Q, and it was working great for a while. Now it is very low volume. It began intermittently but very quickly went low all the time. with full volume it barely drives the tweeter and you can feel no vibration on the woofers. turning to the test setting gets a good loud hum like it is supposed to. we have cleaned the mute and squelch contacts on the mech. removing the mute/squelch plug on the amp makes no difference. I grounded the orange wire on the plug. I removed the 2 6BJ6 tubes out to kill the AVC. that only increased volume slightly. we swapped the cartridge, all to no effect. because it has affected both channels equally I am at a loss of where to go next. Thanks in advance. Mark

First, rock the volume control plug while playing. If Pin 1 develops poor connection it will have the effect of placing the two channels across the input and out of phase.

If no result, do DC voltage checks starting with the preamp. If you don't have a schematic, there are reasonably legible ones here:
http://www.verntisdale.com/Seeburgschem.htm

Rob-NYC