I tried biasing but only got from -11 to -23 mA when turning the bias trim pot. I first want to make sure I'm not doing something stupid - I am very careful doing this and respect amperes, believe me. Shunt method: Connect multi-meter (red) to the center tap of the output tranny. Connect black to pin 3 of one of the power tubes (Svet 6L6 Winged-C). That's it but I can't get -30 to -35 on the meter (only from -11 to -23). 1. The center tap of the OT is red and is connected to the board. There is also a black wire from the OT connected to about the same spot with a short little jumper. Is that ok? The reason I'm asking is because the OT is not original - it is Schumacker 4ohm from 1968 - probably from a bassman. 2. Should the meter be set to V or mA? I am setting for 200 in order to get the reading. If I am doing this right, it's possible that the resistor, the electrolytic, the diode or the trim pot is shot in the bias feed supply, right? If so, how can I know for sure which is fried? I guess the electrolytic should be replaced anyway as it is original 1964 (I've replaced all the caps under the pan, a few years ago). Anyway, thanks for your help on the bias questions.