Gordon Bennett what are you lot piffling on about ?
I did Exactly what he's been trying to do .. For YEARS .
From what your've said it sounds like your've got it right ..SO..
Stop looking for the technical problems and start looking at the obvious....
Got your remote control handy ?
Trying switching between Line 1 / 2 / 3 .. or AV 1 / 2 / 3
I'll stick my neck out and say that little problems now cured !! :-o
:-D