So this is what I'm seeing. When I first turn on the amp, after about a minute of perfect bias left and right, I feel a vibration, and left side of the amp voltage bias drops, and the right sight bias blows up and starts to red-plate the power tubes for several seconds then the vibration stops, bias goes to normal. Then after a minute it does it again.
However, after the amp "warms up" I guess after about 5 minutes it stops, and from that point on for as long as the amp is on, it biases perfectly, and runs completely normal. It's only at start up.
I have the original driver board, and replaced the four coupling caps, and the two .05 caps. And I have tried a couple 7199, even have NOS RCA 7199's. But the behavior is exactly the same.