My Traynor YCV50 has a bad power tube, already figured that one out. I have a matched quad of KT77 tubes, a Garbner Bender multimeter and a eurotubes bias probe. Considering that my tubes are all matched I should only have to use the bias probe on one of the tubes while adjusting the trim pot correct ? The manufacturer suggests setting the zero signal bias to +75mV, now is that number divided by the number of power tubes ? What setting do I need to set my multimeter on ? Do I need an insulated screw driver in order to adjust the trim pot on this amp? Do I adjust the bias in standby mode? Or On ? If you can please answer all the questions as I do not want to harm myself. Thanks!