I was watching this post because I was having the same issue on my Theatre of Magic. I fixed mine - it turned out to be the door interlock switch (the larger one of the two switches). Mine was mis-wired at the switch terminals. I also had to clean the terminals to get a good connection... the switch was actually working fine. Now I have flashers!

BTW, you can't do a flasher test with the door open, unless you depress the interlock switch.

I won't be in front of my machine today, but this is the door interlock switch that enables / disables the high power to the driver board.

If you look in page 3 of the manual it shows you how it is to be wired. Check that, and inspect the wire terminals and switch blades for good contact. I actually removed my switch, tested it with a MM and removed some corrosion from the switch blades. If that doesn't fix your issue, look at the driver board and note the on/off status of the LEDs. I think LED 5 (?) is the high voltage indication.
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