Thanks for all the replys so far.
ShyTorque. The blades slow down and start up at the same speed as on any jetranger I have seen.
jeffrey1. Very usual information.
I did some autos in the machine yesterday to check auto RPM and it was fine. 100% with collective down so no dramas there.
I have been told that the problem could be something as simple as a small object lodged somewere in the actual line running to the torque gauge. And apparently to retreive the "object" you have to pull the whole accessory gearbox apart. Any views on this?