[Radioroslyn]

Well what's happening is the coil you wound for the IF transformer is resonant at 680 or so when it needs to be at 455kc. If you hook the ant to the cap of the 6K7 the tuning cap is not in the circuit. SO the 680 kc signal comes down the ant and goes into the grid (input) of the 6K7 gets amplified and then get detected and on to the audio stages.
Two things to try. Hook up your generator at the tv input and adj it for 455kc w/modulation. Peak the 4 trimmers on the IF transformers. Then try the main tuning to see if you get any BC stations.
If that doesn't help add another 100turns to your coil and see if you can get a sharp peak when adjusting the last trimmer.
Short of those two things find yourself a 455kc IF transformer.
Terry