Been having issues with my Ampeg, brought it up on the forums and I started with the tubes as they were about 10 years old. Got definite improvement once the new tubes were in (thanks guys) but when I went to set the tube bias I noticed that only Bias 1 is active with lights, Bias 2 doesn't light up, neither the red or green led light up. I noticed that there are some other smaller tubes above the Bias section in Tube Complement, a row of small tubes inside the cage, on the board. One of these 12AU7 tubes isn't glowing. I switched the two 12AU7 tubes to see if the same tube was in active and it did not glow in either slot. When I play through the amp, these LED's now light up as the tubes have been switched. Manual says if there are no LED lights - Possibly no High Voltage - Bad Bias Control - Bad Tube(s) If this 12AU7 tube is replaced, should I replace the other as well? Is there a direct connection between these tubes and the Bias controls?