Looking for a little help with this. Recently retubed my Orange AD200B. Now biasing the amp I'm getting some strange (to me) readings. The output tubes are in pairs 1+3, 2+4. I can bias tubes 3 and 4 to Orange specs 18-20ma but tubes 1+2 show only 5ma. Swapped around the tubes, swapped out the PI tube(12AU7) doesn't make any difference. Is this normal on this amp? Checked under the hood for burnt resistors bad solder joints, etc.. Can you guys give me some insight.