[keith6989]

OZ4 is the power supply for the speaker, It could be that, the vibrator, or a tube in the radio, the vibrator (big silver thing) should be making a faint hum, and you can also feel the vibration. If the oz4 is a goner, you should probably replace that with solid state. eBay is a good source for tubes, there are also some schematics online for it. The pulsing is probably a weak tube, I have a spare set of everything if you have no luck on eBay.

Keep me updated on how it goes.