[Reece]

I'd find it helpful to draw the internal parts of the tube on the diagram. It's easier to trace that way than to stop and think: hmm..pin 5 goes to ..what? Forgive me for this really obvious suggestion, but do both parts of the tube test good?

I know you've gone over the wiring time after time, but something I've found helpful is to trace each circuit and then mark them off one by one with a highlighter on a copy of the schematic. I have a 1920's TRF on the bench right now that somebody had got into and this is helping me get the wiring back to original.