Rockola speaker power distribution unit - pot cleaning

Last one, I promise...
Rockola 425.
Have a bunch of distortion in the upper left speaker. After pulling EVERYTHING apart, finally isolated the issue to be in the Speaker Power Distribution Unit.

There is no distortion in the Lower left speaker, but there IS distortion when I hook a speaker to the External Speaker contacts, leading me to believe the issue is with the internal volume control pot. More precisely, in the upper pot of the two in the stack.

I'm able to get inside the lower pot no problem, but the upper pot wont budge. Been putting a lot of force on it and am afraid I will damage the whole thing if I'm not careful. Is there any trick to get this thing open?

I question whether that post would cause "distortion". It is a passive item. These faders are an idiotic holdover from the era before 70 volt audio distribution was standard and they just cause erratic operation.

I always eliminated them in both R-O and Wurlitzer.

According to this schematic: http://www.verntisdale.com/schem/424-26.jpg the gray-white and gray-red wires come from the arm of that pot. trace out the wires from the transformer secondary for each channel, remove the wires from that pot and connect each channel directly. You can leave the pot for appearance if desired.

Rob/NYC