What position are the AR switches in?
If in the AR position, then when the button is pressed the gate should be present on pins 3 and 12. Pin 12 looks right but pin 3 is showing only 0 V. If the switch on that side is in the AR position then something is wrong with that input. Check continuity from push button to switch to resistor to diode to pin 3. With power on and button pressed there should be +12 V at switch pins 1 and 2 (latter is your G1), G6, and F7, and about +10 V at F9.
Additionally, if there is -12 V at pin 1 and the R pot is all the way down, pin 5 ought to be about -10 V, so it seems like there must be something else wrong there, but focus on the input for now.
Schematic (for Sam’s single AD/AR version):