Re: Damsel in Distress! Head Light adjuster MOT failure.
I'm not familiar with 156 headlights, but if the adjusters are the same as those on a 145 they can be fixed.
On the 145 there's a plastic bevel gear with a hexagonal hole in it so that adjustment can be made using an Allen key; this drives another plastic bevel gear on the adjusting screw. Over time the screw rusts & seizes in the headlamp housing - the bevel gear then just turns on the screw. I cured mine by removing the bevel gears & giving the screws a daily dose of penetrating oil for a week or so until I could move them. If you can do that, all you then need is some sort of collar you can fit on the screws to stop them moving in & out of the housing & to give you somethiing to turn them with - I used the terminals out of an old 13-amp socket!
Where are we going & why am I in this handcart?