964 intake resonance valve rattle..

[nicholasg]

Dear all, my 964 c4 coupe, manual, 1992, 150k miles, plastic intake manifolds, (runs well bar a little hesitation at low revs 2-3k), but there is a rattle from the top of the engine coming from the actuator that controls the resonance flap. If I reach in and hold the rod from the actuator the noise goes away. I can also move this rod by hand, so it is not held firmly in either the open or closed position but it is connected.
There is a characteristic "click" when I turn the ignition on, but it's not coming from this actuator which doesn't move when the ignition is turned on.

My questions is - do these actuators fail (a $100 part) or do the flaps inside the intake fail ($2000+ part)..

Has anyone had this issue before? Is there a good way to verify where the problem is before stripping the intake off the engine?

Thanks very much

Nick