Just had a fruitful couple of days playing around with the seized headlight adjusters, lots of patience and WD40 and now they are moving freely, need to pack some grease round the threads now ready for winter. It's very easy to strip and damage them if you don't take care. If you have not done this job before, the vertical threaded screw should turn the gears inside the small plastic gearbox, the horizontal thread does not turn but moves on the threaded sleeve inside the plastic housing. I would suggest taking both headlamp out before winter and putting plenty of lube on the adjusters before the weather gets at them.

 

White lithium grease works great.

 

Yes of course, need to get some, just used LM, better than most.