I had a similar problem with the headlights locking in the down position for a while then after several days would correct itself. Did 4 or 5 times. Turned out it was the SmarTop I had installed. I took it off and no more problems. However the side to side movement still does freeze up occasionally even after took SmarTop off so unsure of correlation there.

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'11 Z4 35is
'09 Audi Q5
'07Lamborghini Gallardo