There are several amp book out there, like "How to Service Your Own Tube Amp", and "Inside Tube Amps", and a new one by Gerald Weber, although I don't know if I'd be comfortable with his writing style if it is anything like his self promoting. Sometimes he comes off as too smart for regular folk, and that may make for a difficult read when your amp guts are hanging out of the chassis. But I haven't seen his book so it might be awesome. The price of the books are all around $30, same or less than a bias job, and you should get a lot of other good info. I knew how to do it once, a long time ago, but I always had amp guys around me who did it for free and I just plain forgot. I've had my main tube head for over 15 years and it was biased for the tubes that are in it about 5 years ago, so I'm sure someday it will come up. I just record with it now so the power tubes will last quite awhile. Incidentally, if you do get a book, maybe you can give us a review.