I say 'seems' because I have the feeling the wandering bias is not caused by the tube itself. I did switch the output tubes and it didn't follow the tube.
when biasing this specific location I can see the value going up (and down) between 100mV and 1100mV. only when I hold the red pin of the multimeter a certain way does the voltage stop wandering around.
has anyone experienced this before and knows of places I should check first? to me, it seems that this could be related to a losse solder connection or something of that nature, but may it well be a faulty resistor?
I appreciate any pointers you can give me.