Quoted from shirkle:
Is it possible my beacons are pulling power away from that VUK coil somehow?
Beacons are 26 vac and the VUK coil is 50 volts dc. But the VUK coil is turned on by a snubber relay, this relay is powered by B+ which comes from the same winding that power the beacons. I would check the connector 6P1 in the cabinet for a poor connection on the red wires. Then I would remove the snubber and look for cracked solder joints.