The manual says:
6.3 volt heater wire.
Make a twisted pair of red and black insulated wire. This can be done by hand or by clamping one end of the wires to a bench and chucking the other end in a drill. Try for roughly three twists per inch. The final twisted pair should be 9 (225mm) long. Strip all ends back 1/4 (6mm). Connect the black wire to power transformer terminal 10 at one end and pin B4 of the nine pin socket. Connect the red wire to power transformer terminal 12 at one end and pin B5 of the nine pin socket. Solder all four terminals.
But, the picture shows the red wire connecting to terminal 15 on the transformer. Not terminal 12. Am I missing something?
Thanks,
Toby
