OK, if I were troubleshooting the radio , here is what I would do next.
First, on the straight back radio, I would remove the front cover. This would also mean disconnectng the speaker and reconnecting it with jumpers. Next I would use a voltmeter to check certain areas of the circuit. It is handy but not essential to have a tube tester. A spare set of tubes can do the job too. Also, you would need a copy of the circuit. I can Email you a copy if you need one. If you want to proceed, I can help to giude you through the process. Otherwise at this point, I would suggest taking it to a repair shop.
