Thanks for the replies, I get what you're saying however the vacuum plunger 'dosent' return to zero position that's the problem.
At idle the position sensor reads 0% as does the request then above 3000 rpm the plunger lifts, sensor reads 99.95% as does the request but when you let off the plunger remains in its current position as does the sensor percentage position and the request drops to 0% and the fault code returns?

I have removed the manifold since posting and see nothing conclusive? One of the metal separating plates which slide into the head is missing a rubber locating sleeve down one side, and the flap shaft has some sideways movement (approx 3-4 mm) and the valves are reasonably well caked in carbon as our the injector tips.

When you say bushings do you mean either side of the flaps themselves?

Thanks again for the replies keep them coming I can see this one turning my hair grey, customers already a fair few pennies In from the timing chain replacement

Regards

Luke Browne