I can't tell by looking at the tube where the internal wire that comes off pin 1 goes because the internal surface is coated with a gray RF spray. The glass is clear for only about 1/8 inch before the tube goes gray so I can only see that it goes straight up but that is all.
There is as far as I can tell 2 possibilities:
1. Pin 1 is connected to the gray sprayed on shielding.
2. Pin 1 is connected to some othe internal components of the tube that will see voltage.
How owe these two possibilities will interact with the preamp is unknown to me of course.
Is there a way to test the pins with a multimeter to shed any more light on the subject?