Well folks, I can now see the light at the end of the tunnel with this CFS.
It has been a challenge to say the least, but have been looking a round the forum on good days.
The good news is that I have also spent my time wisely and discovered a different style hinge which I decided to try after many mock ups of the original hinge I made with no success.
When I say no success, I really mean not enough improvement for it to work without scraping or binding.
The alternative hinge I plan to use was discovered quite by accident and had been under my arm all this time as it is being used in a console to the side of my TV chair. I rarely open it but was looking for the lost remote controller and opened the lid and the penny dropped.
I thought that discovery was going to be too easy, if it worked.
I took the pair off my console much to my wife's disgust and installed them and made new mounting brackets.
I could not be that lucky of course as they did not work either, but I could see their potential and have started modifying them to see if I could get them to move slightly differently and that is where I am right now.
If this fails I will definitely walk away from the idea of a firewall hinge.
Stay posted...