Quoted from blowback1976:
So with incandescent flashers in, it is still doing the same thing, and failing during the same tests. Are the warming resistors the ones on the Flash Lamp boards?
Hmmm. OK appears not because of the LED flashers then.
I just noticed a possible clue.
You said the flashers are coming on with the A/C relay selected. You also said you replaced the snubber boards and flash lamp boards. What I have noticed in your last post is you say the lights are coming on when the coil test enables the A/C relay. Nothing visual should happen here, all that should happen is that you hear a click of the A/C relay in the cabinet.
When the relay clicks, It puts power on "C" for the flashers. In test mode, the flashers should not be coming on, because the transistors should be off. In coil test, too...when those coil tests are run, the A/C should be on the "A" side for the coil only when the solenoids are fired. Somehow, the flashers are also simultaneously getting power.
I'd be taking a closer look at the A/C relay board. (miswired? shorted?)