Again. Thanks. I must be going insane. I checked those fine comments and my tetrads fit perfectly. I typed them in again to google and bingo, there it was. I must have typed them in wrong before but I tried several times. This must be what happens when you turn 50. Right. I'm off to see what I can make of the closed chord. I have a feeling I might be back!
I am absolutely stunned by the complexity of this thing. It makes me laugh to see comments about the quality of the puzzle. Sure, the wording is a bit ambiguous, but I cannot begin to imagine how one would start to create puzzles like this. Maybe if I did a few more I would understand better and people's comments would make more sense, but I normally give up after 10 minutes of drawing a complete blank!
Thanks again....and watch this space!