Old thread, but as relevant as ever!
I had the bongs, messages, reduced performance and fault codes to suggest I had a stuck actuator.

Got under the car yesterday and, indeed, the right-side actuator was stuck. Quite easy to get to with the undertray removed. A 12mm spanner fits nicely on the arm of the actuator and I managed to loosen it up and work it free. I soaked it with wd40 and chain lube, which penetrates well and doesn't evaporate.
All good again! 😃

Mine is a 2007 lhd 3.6. I don't know how much changes underneath between lhd and rhd, but if it was the left actuator stuck, I'd have been in deep trouble. With your head arranged just so, you can just about see the lower half of the vertical link. But getting at it with a meaningful tool? You'd be very lucky to succeed. I managed to prod it with a length of tig rod and happily, I could see it moved with ease. I soaked it with penetrant and chain lube and thanked my lucky stars.

I can't overstate the value of this forum. Whatever that car throws at me, some kind soul has been there before and taken the time to describe exactly how it can be fixed.
Thank you all!

Cheers,
Henrik