The bias supply on these is derived from one half of the ac HT (that white wire from the rectifier diode block). The bias circuit needs to see this voltage as soon as standby is on (before standby is powered) but if you have moved the standby switch so that should be ok. If the B+ is higher than usual (400-420v is usual on these) ie if the PT is a later 1202-324 from a JCM era then the stop resistor (47k) is the one to change to get into the correct range for the tubes you have installed. Suggest for now you tidy up lead dress and then piggy back with croc clips across the 47k to get closer to -40 to -45v range on pin 5. Then you can decide if you are going to mod the amp to fit these old tubes or get a burned in fresh pair and set up for those once you are happy, my 2cents.