John Greenland
CVRS Member

If you blow up the pic, the 2 heavy red leads are connected to pin 7.
That means the plate is between pins 1 and 2 on one side and 6 and 5 on the other.

This would separate the plate and grid 2 (both higher voltage and probably higher signal level leads) from the other leads.

Why ???— The previous member’s idea sounds good to me.