Ok, you got my curiosity up when I saw this pic. I couldn't think of any reason for Williams to have 30 volts AC going to the play field, so I looked in my pin and found this same connector. I followed it and it only loops back up the the backbox. This pair of white/blue wires are connected thru the play field connector and with the play field not connected this has caused the break in the circuit going up to the replay thus stopping the beacons from turning on. The jumpers that you installed is the same as if the play field is installed, so with the jumpers in the beacon will work again.
pasted_image (resized).png