Disclaimer: I am somewhat of a System 11 newb and so I want to clarify a few things.

I have one flasher that isn't working. It occasionally worked and now has quit entirely. It is the Right Ramp Bottom Flasher. That is on the "C" side of things. The "A" side is the knocker. The knocker works fine.

Does this tell me that Q23 is good?

Also, could this be an opto isolator on the interconnect board?

I have tested the diodes on the aux driver board and they test good D39 and D40

The connectors look good and don't engage the flasher when pushed on.

Any direction I should go here? Thanks for the help!

Yep, bulb is good.

So, I measured AC to the bulb and put one lead on each lug. I wasn't getting any voltage in either direction.

Sounds like its time to reflow the relay board?

Ok, thanks. I tested both voltages and got nothing on either. I'll test DC again.

The relay board is that same as the Aux power driver board?

Ok, I tested voltage to the bulb again during test mode. I only VERY rarely get voltage to the flasher and it only works very rarely during gameplay. I reflowed the Aux driver board just to make sure and it didn't help things.

So, I'm thinking it is either a connector or another component on the MPU.

How do I test the ground path for Q23? Do I test for continuity between the ground on the socket and the ground leg of the transistor? Not sure on that part.

Awesome. Perfect example for my simple brain. Thanks wayout440! I'll post my results. I think this will probably be on the interconnect board. It was totally fried when I got it and I had to replace 5 or 6 ceramic resistors and there is probably a spot I missed.

Fixed it. Thanks wayout440 for the help. I tracked the issue to a bad trace on the interconnect board. I reflowed the connectors and resistors and then tested the continuity from your diagram. Got continuity all the way from the socket to the diodes on the driver board. Fired it up and then it wouldn't start a game. I thought I had totally screwed something up but found that one of the wires on the start button had detached. lol

Flasher works great now.