850I head lights

have a 850I, running great except every few months something new comes up.
one of the headlight is not coming up all the time, i have to play with the switch back and forth.
sometimes the other one will not go up or the same one causing trouble on the right will stay up.
could it be the the switch inside the car or the actuator " motor" for the light itself, is there any relay for those lights may be it is the problem?
if someone could let me know where to start here before i start buying all the parts.
sincerely
Stephan

There is a relay. A tall relay toward the middle of the box. K39--swap it with K46 and see if the problem moves to the High beam lights. If it does the relay is bad. If the problem is fixed the contacts were probably dirty.