I'm seeing something here that happens fairly frequently on the forum. PB asked you to try just the 12AU7 and you responded that you tried something different, both tubes installed. I guess it happens because we are sometimes not precise about what we are suggesting (this long distance troubleshooting stuff is without a doubt tricky) or maybe suggestions get read in a hurry. If you can go back and try what he suggested - just the 12AU7 tube installed - it may offer some useful info.