Ensoniq SDP-1 volume issue

I am working on an Ensoniq SDP-1 that has a volume issue. The service manual and schematics leave a lot to be desired. It passes all the test in the service manual except for the burn in test. I get no sound from the Left, Right, or Bass; and the volume on the headphones is barely audible. I cannot tell if it is having any other issues with the voices due to the volume. I have replaced all of the electrolytic capacitors with no change. I checked all the voltages and they are in spec however the manual says to check +12/-12 for ripple which I am not sure how to do. The question - Can anyone help guide me? The solution in the manuals are to just replace the boards which is not really an option. Just looking to learn more repair skills.

Solved: Bad volume slider pot.