[VntgRads]

OK, make sure your bulb didn't just get burned out.  Then mount it back in the top area where it belongs.  Can I assume the radio still has the 2 wiring connectors (one with 2 speaker wires & one with the blue and yellow wire)?  If so, connect your positive lead from the power supply across the 2 "prongs" on the connector with the yellow/blue wires.  Use the nut/bolt coming out of the back of the radio for your ground and then try it (with a good antenna).  You were able to get some hum previously so your ground was OK and you had the power lead hooked up correctly.  But you should be able to tie the blue and yellow wires together and have the radio and light work without mishap.  If not, something is not wired correctly.

Craig R