Look at the note.
Voltages referenced the negative filament pin.
Note the screen is tied to the negative filament pin.
Reversing pins 1 and 7 should make it work.
Note the circuits and you can see the negative filament supply is grounded and the pin with the screen is grounded.
It could well be all we need do is reverse the filament battery.
** Pin 1 negative and grounded. Reverse the battery and swap pin 1 and 7.









