I had a similar problem on my 145. I cured it by taking the height adjuster control out of the dash & giving it a good clean with contact cleaner. You may get a temporary cure by working the dash control from high to low & back a few times.
If that doesn't work, try looking for bad connections or a bad earth at the headlamp.
I have had the exact same problem on my 04 147 - left hand side.
Motor continually running - i tried manually adjusting the headlight to get the motor to stop, but it only worked in the short term.
I took it to the main dealer here and they are replacing the whole headlight assembly. I was under the impression that you could buy the motor individually, but as it's a warranty job, i am not so worried.