While fitting my new door mirror glass in the dark, I noticed my nearside headlight adjustment motor is running all the time but only when the level adjuster is on number 3.

I have normal headlights not Xenons (with better bulbs!)

Any guesses why the motor runs all the time on this setting ?

I have removed the headlight bolts and checked its sat on the plate properly and seems to be, if I adjust the level switch the offside moves fine, the nearside doesnt

Assistance much appreciated.