Hi everyone,

I am back on this after a long break. I have replaced the diode but unfortunately the buttons still don't work.

Is there a way to simulate activating the buttons without actually pressing them so that i can determine whether the problem is with the buttons or somewhere else? Any other ideas?

Thanks, SV.

Unplug IJ4 on cpu
Short CPU board, 1J4, Pin 2 (GND) to Pin 3 (ADVANCE) that is the momentary switch: each time you short these 2 terminals it will simulate pressing the red button with the orange and green wire.
A jumper across 1J4, Pin 2 (GND) to Pin 4 (Auto / Manual) Will simulate the black middle switch being in the up position. No jumper across these 2 will Will simulate the black middle switch being in the down position

Before trying this disconnect the memory protect switch that the door pushes on when it is closed (if you have one fitted) if this is stuck closed it will enable the memory protect and the Advance button will not work.
Also Before trying this try shorting the Green and Orange wire with a screw driver, this will simulate pressing the red ADVANCE button. I have seen these switches fail on many occasions.

The Button with the diode on it is the "HIGH SCORE RESET" Button. No need to worry about this switch at this stage.