Electric motor
 

On the back of the lights you have the electric motor but what does this long screw do as turning it seems to do nothing .
http://tapatalk.imageshack.com/v2/14...a4e812a089.jpg

It adjusts the angle of the headlight, needed for MOT fine tuning. Takes ages to move it though, requires shed load more turns than a manual one to do anything.

Also as I found out for Hiho's MOT, the balls can pop out of the sockets so they don't do anything. Easy way to check is to take the bulb out and look through the hole.