Another quick test - I connected the 9XR and Frsky to the KK2 to rule out the radio.
It all works just fine - I set up a new model for the KK2 and it fly's great thrashing it around in the garden.
So - it must either be:
Naza faulty
or
I have set something on the Naza wrong? But it flies ok before it crashes....
In the 9XR I have channels set up as:
1 = THR
2 = AIL
3 = ELE
4 = RUD
I guess that it does not matter which channel is assigned to which control as long as they are plugged into the Naza in the right places - and they were otherwise it would not fly!
I'm 99% certain my Naza is the problem now.
Had no reply today from quadcopters