I have a 91 420sel and the rt headlamp keeps burning out every couple months or so. The left headlamp has never gone out. A while back a piece of lumber hit the lens and cracked the glass. Since then the light has been acting out. I have already ordered a new lens/reflector and plan to replace it this weekend. Could this crack somehow be the culprit with the headlamp going out constantly? What else could I check? Thanks in advance.