Thanks for the replies guys .
Vacuum supply and control are fine ( road tested with gauge in line to the control actuated supply) full vacuum at low speed which decreased as engine speed increased till full throttle and 0 vacuum. ( am i right in thinking these will revert to full boost if the vacuum supply is lost?)
There wasn't as much movement on the rod as that 10mm at the most?
Anyway i gave the innotech turbo cleaner a go which lowered the peak boost (still slightly higher than specified value) customer has agreed to try out under the condition should the symptom return a new turbo will be required. has been a few days and i haven't heard back so fingers crossed