I’m not sure if you received a schematic with the kit, DH never provided one, but I’ve seen one or two floating around the net. If you look at the chassis layout provided in the book you see that the twisted pair goes from V2 (the power tube) to V1 (the preamp tube), one side connects to pin 9 of V1 the other side connects to pin 4 or 5. Pins 4 and 5 are jumpered together. This completes the 6.3 (heater) circuit in the preamp tube. Heater circuits are not included in most schematics for clarity.
Here is a link: http://www.freewebs.com/valvewizard/heater.html
It is important to understand the use of a tightly twisted pair of leads for the 6.3v circuit and the use of the 100ohm resistors as an artificial center tap if you transformer did not come with one for the 6.3v taps.
The 2Stroke can be hum and noise free if you are careful with the heater circuit and the grounding layout.