Didn't take long to diagnose this part failure, don't think it had ever been changed, the inner metal cylinder just fell out..
So with the same amount of swearing as prescribed by the other accounts I read, I managed to fit a Powerflex by hand, which has solved all the relevant issues, but now I have this vibration at idle which pretty much exists in every car make that has one of these fitted.
The bolts were tightened to correct torque.
Is there any way to eliminate the vibrations when idling or should I just refit a new OEM one?