Echo Amb Bias Confusion

I just got an early '70s Japanese Echo Custom Amp 30 head, and I'm very confused about the bias system. All the amps I've worked on have had cathode bias, with a cap and resister from the cathode to ground. This amp seems to the same, except the cathodes go straight to ground -- no resistor or cap.

FYI the power tubes are 7189s, the original Matsushitas. Actually all the tubes are original Matsushitas. I started looking at the bias circuit because the plates glow red. I thought maybe the bias resistor had drifted. Also FYI there's no bias pot.

What next? I have no idea what could be causing the glow. Certainly there are some bad caps & resisitors in there, but I don't even know where to start looking.

Thanks in advance guys...

Attached Images

echo-custom-amp-30-schematic.gif (89.5 KB)