HELP , More problems with Bias

Thanks to everyone's help I now know how to set the bias on a tube amp. But, I now have a problem with one channel of my Golden Tube Audio SE-40. The left channel biased without a problem just like it said it would in the manual. The right side, however, is a different story. Each side has three adjusters and three places to take a reading. The reading according to the manual needs to be between 635mV and 640mV but never higher than 640mV. None of the three testing places on the right side are able to be adjusted down to 640. one will go as low as 720, the other two only go down to 950 and 1.045. I hope that someone is able to tell me that this is a tube problem and not an amp problem. What happens if I play the amp with readings in that range? Should I just buy new tubes? Any help would be appreciated, I would sure like to hear my new amp.