Anybody feel like discussing Old Mopar/Motorola hybrid AM radios?

I've got a bad feeling about trying to troubleshoot this radio until I better understand the circuit's theory of operation. There's too much risk of going off on a wild goose chase in troubleshooting unless you really understand how the radio works first.

So did we ever figure out how the bias is being handled in this receiver, or are the tubes being run "full tilt", without bias? In the case of the amplifier tube elements, in what class are they being run?

I'm going to ask these questions to some of my friends who know more about electronics than I do. Also, there are some websites concerning space-charge tube circuits that I need to look at again.

However, most of the academic literature concerning space-charge tubes is written in Russian, because U.S. manufacturers only made space charge tubes for a few years before switching over completely to solid state. The Ruskies continued to use them, though, and eventually developed, to a very high level, fingernail-sized subminiature space charge tubes for their satellites before they switched over to solid state radios. Their space-charge tube satellite radios actually outperformed the solid state ones that they later used in their satellites.