The passanger light started flickering again and then died and can turn lights off and on and will get brief flicker again so fuse must not be blown. So, it seems it may be the ballast. Can that be replaced w/o removal of headlight assembly and save the $2500 dealer would charge for a headlamp? I did read that in older models the ballast could be replaced. I'm handy but there are limits so will have to have to take to a repair shop but don't have much confidence in their fix vs repair ability.

 

If the bulb is flickering then going out each time you turn the switch ON, then the ballast/ignitor (aka HID controller) is dying.

The ballast is mounted underneath the headlight assembly by three (3) screws:

You WILL have to remove the headlamp from the car in order to swap out the ballast.

Here is a good DIY thread on removing the headlamp.

I still would not take it to a mechanic or dealership unless you know for certain this is above your skill set. It is not a hard job, but it can seem overwhelming.