I made some assumptions about my amplifier. I do not have access to an unmolested one. The 923 photocell uses pin 2/4. The schematic is unclear. I assume something was done in the mess of wires that I can't see in pictures, or a different tube was used.
I had my amplifier working with my modifications on the bench. After installing it into my chassis, it did not work. My plug from the chassis to the figure is using 2/3. Those connections appear to be original. This will be modified to fit my needs.
My other modifications were made to suit my needs and assumptions. Your mileage may vary.