Yeah I tried that on my 1.00NX but that doesn't seem to be the problem. The needle visibly "walks" in use, as you move the throttle. You can see that it doesn't return to the same position after you've flown the plane.

The PTS .455 engine also walked out of the box, and fortunately we were able to spot it. It wasn't a spring problem.

Once the walking was eliminated the .455 has run like a champ.