Correct, the shim was missing from the Caliper mounting bracket!
When I braced the swinger I had to use a CBR 900 Caliper bracket and I left the brake pad to caliper bracket locating shim out.
Have done about 7000 K's since I did the swinger mod and was never happy with the back brake.
It was even worse than before I braced the swinger and even then it was shite.
Hopefully there will be an improvement.
Have to ride it to find out.
Just as I suspected, no shim .
Shim is fitted now and all is correct!