My 1995 Hyundai developed an annoying flickering headlight problem recently, where the slightest bump would cause the lamp to shut off. I tried reinstalling it and repositioning it, but the problem did not correct itself.
I further read up on the phenomenon, and a few websites suggested coating the contacts and rubber seals with dielectric grease. This is a non-conductive lubricant that helps seal out water and ensures a better connection by creating a tighter connection.
Anyways, after slathering an abundant amount of dielectric grease on the seals, boot, and points of contact, the pesky headlight began to cooperate. On a 10-mile drive in the dark tonight, I generated nary a flicker, and the lamp stayed lit the entire trip.
Thus, I heartily endorse dielectric grease in the installation and replacement of automobile headlamps. Now, if I could just find a similarly inexpensive solution to a leaky house roof.