Re: Headlight adjustment
It's quite possible that the adjuster screw has seized in the headlight housing. If this has happened, the driven plastic bevel gear will just be turning on the screw rather than turning the screw.
If that's what's happened, it's a relatively easy fix. Take the bevel gears off & see if you can turn the screw with pliers. You most likely won't be able to, so it will be necessary to free the screw off; apply penetrating oil & repeat until you can turn the screw - this will probably take a week or so of daily application. When you've got the screw freed off you'll need some sort of collar you can fit onto it to prevent it moving in & out & to give you something to grip to adjust it. I used some terminals out of an old 13-amp socket!