What leads to twist

[benoit]

Please correct me if I have errors or omissions.

PT Primaries and secondaries
OT secondaries NOT primaries
Choke ?
Heaters obviously
Anything else carrying AC voltage (i.e. to a lamp)

[marshmellow]

I also twist the leads to control grids of the power tubes if possible. And both primary and secondary of the OT.

But on the other hand, you don't really need to twist the power tubes heaters, you can also put them straight from one pin to the next.

[Andy Le Blanc]

wires that carry AC from the PT.......only ....... everything else should be
laced to form a harness(s)....