I'm not a pinball expert, but looking at that schematic, the zener diode VR1 is a critical component that could cause these symptoms, and it's not a part you can test with conventional test gear. Basically, it will read like a normal diode one way, but then when you apply 140V across it the other way, it will 'break down' and start conducting. You can't properly test it with just a multimeter.
Given that you've changed all the other semiconductors, and tested all the resistors, not sure what else it could be.
Given that you've changed all the other semiconductors, and tested all the resistors, not sure what else it could be.