Thank you John really appreciate your response.

I have been concentrating on keeping a grip/tension at the aperture corners and it seems to be working.

I have been concentrating on relaxing the body so much I have forgot that I need to keep tension on the aperture.

When the quiver does come I have got rid of it by putting some vib on and it has stopped it. I am still working on eliminating it but this is a performance anxiety related problem and I will need help with coping mechanisms.

Thank you John and good luck with your journey.