Weird Bulb Behavior

Here is what I found on pre 70 cars with dash ignition. Turn on the flashers. Turn on the turn signal. Turn on the radio. The radio will play but go off and on with the flasher. Hit the brakes and the radio will play constant. When the flasher and the turn signal are on they back feed the Accessory circuit. The brakes bypass the flasher. Look for a short in the turn signal switch since its one side only.