My passenger side headlight (low beam) is aimed much higher than the driver's side. The bubble on the driver side is all the way back (low) and the passenger side is all the way front (high).

However, turning the adjustment screw (in either direction) does not appear to make any difference in the aim.

Anyone have any ideas?

 

Yeah, play with the side to side adjustment. They appear to be interdependent to some degree, especially as you approach the limits.

 

sounds like you have stripped the worm gear for the adjustment screw. And how do I know that you ask? Pop out the headlight, take off the back piece and then watch the adjustment screw turn (or not turn) as you turn the adjuster. You can pull off the adjuster (metal) and examine the gear (plastic). I'll post a pic in the AM (of my stripped gear!). Don't know if gear can be replaced, I bought a new headlight assembly