Check around the dimmer switch for loose or dirty connections, or high resistance contacts in the switch itself. They're bad about developing dirty contacts and making the headlights go dim, or quit altogether.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!