rover 400 headlight height adjusters

just changed one headlamp yesterday because the glass were miscolored. then I turned the light on to check if the height adjusters worked and they didn't exactly. they were "flickering" up and down and didn't always respond to the switch, sometimes they went the wrong way when I moved the switch. what do you think is the problem? is the motor in the "new" headlamp broken? is it wiring? or the switch? it doesn't normally do this.

from the last news http://ift.tt/16wqDDz

via IFTTT