Ok, I popped the hood this morning and here's what I found...
I had already installed a 1M grid stopper on pin 7 of v4 so not the issue I guess.
Most pin voltages were right on target but pins 1 and 3 of v4 were a little low (211v and 2.1v respectively).
Pins 1/6 of v2 were below 400v at 383v
While I was in there I re- routed the anode wire of v3 so that I could bundle the anode/grid/cathode wires for that triode. I also collected these leads on each of the other pins. I re-flowed some solder on a few joints to be sure and I checked the bias.
Here's the interesting bit. The bias was set way low at 15-16 mA. The power tubes are getting 410 volts so it seems like the bias should at least be 21 mA to be in range. I upped the bias to those tubes so that they were getting 21.5 mA and 22.3 mA and I buttoned her back up.
To my ears the sound I was talking about has disappeared. I wonder if I was getting some crossover distortion because the tubes were so cold?
I can still hear that the speaker isn't quite giving me everything I need and that there is a slight buzz from the speaker, but it sounds mechanical and not electronic. I'm thinking about going with a 50watt weber or a ragin Cajun so that I can Let the cleaner side of this amp shine. Any recommendations?
I'll run it some more and report back.