Ok, so I have checked everything I know to check here, and the siren still doesn't fire. I checked the relay coil with a meter, and it tests fine. I also clipped the diode and checked it, again, it is fine. I tested continuity of the wiring from the coil to the A3J5 plug on the driver board, no problems. Driver board is a new Rottendog board, so I am assuming the related transistor is ok. The A3J5 connector pins look ok, but I guess that is always a possibility. The one thing I haven't done is the ground mods, but they are on my list. Everything works fine on this machine except the siren, and I believe, the knocker. Again, the siren works if I manually activate the relay.
Perhaps the ground mods will fix it, but is there anything else I am missing?