2014 350 GS door mirror won't adjust
 

I have a 2014 GS350, and my first "breakdown". The driver's door mirror won't adjust left to right. Up and down works OK.
I tried spraying behind the mirror with WD40 weeks ago, and today with a more penetrating spray. No improvement.
(I had used this method successfully on an older BMW years ago).
Does anyone have suggestions? Do I need a new mirror? Thanks for your help. Ray