G-System control board volume and expression inputs not working


I am running FW 4.05 R1781.  The vol/expression inputs on the GFX01 rack unit work fine.  When I move the same pedals to the inputs on the control board, no dice.  Won't even calibrate.

When I connect the pedals to the control board, I do not have anything connected to the vol/exp inputs on the GFX01.

My G-System is pretty old, Ser No. 6532013.  Before they started making units with the new input buffer circuitry.

Does anyone know if there is or was a hardware bug with these inputs on the controller board?  Something that can't be fixed with a FW update and requires popping open the controller board case to rework a circuit?  Perhaps was fixed in newer units?

If anyone has the control board vol/expression inputs working it'd be great to hear from you.  I'm looking for tips and insight on how to get them working.

Hope to hear from some experts!  Thanks.