Another, and hopefully the last update on this issue of my car.
After racing the car last night I'm confident to say that the issues have finally been solved & rectified.
My friend and I believe that a slightly tweaked/bowed lower cf deck was the cause of my problems. The problems of the noisy gear mesh, binding feeling and inconsistent handling are now all gone, and it was somewhat a great relief to know that the issues are gone along with enjoying driving the car on the track.
Again, thanks to all who offered advice, help, suggestions and even physically to look at the car. It's surprising to see that even the smallest amount of tweak can have a dramatic effect on the car.
Now I can actually focus on fine tuning the car to get some better performance & handling, I need to work on getting some more traction on the front as the rear just has so much grip!
Cheers
Rob.