The bios adjustments are critical, especially if it is run at high volume, and the original transistors must be used. The only solution that I can think of is measure the bios voltage on the good side, you should have one or two pods right near the output transistors and see how they match up with the problem side. I find that using a sub replacement usually will get you into trouble because the bias is not a match and the hfe is to low "output" Long shot have you checked www.nad.com for customer support to see if they can offer up the procedure in a download.