Dear Tom and Ray:

I have a 2000 Subaru Outback wagon. Recently, the passenger-side daytime running light and low-beam headlight stopped working. When I got out of my car to check that the headlight was out, I happened to bump the front of the headlight casing and -- lo and behold! -- the headlight came back on. I opened the hood and tried to see if any wires were loose, but it did not appear so, and tugging on the wires does not cause the light to go on or off.

So now, whenever I start the car and the headlight isn't working, I simply get out and give the front of the headlight casing a bump -- Fonzie-style -- and that usually does the trick (sometimes it takes two or three whacks for it to stay on). What could be causing this, and how can I fix it?

-- Steve

TOM: You can fix it with a new headlight bulb, Steve.

RAY: I'm guessing the filament is cracked and is separating slightly when the bulb cools off. And somehow, when you pound on the headlight casing with your fist, you're getting the two parts of the filament to make contact again.

TOM: But eventually -- probably by the time you read this, Steve -- the bulb will fail permanently, and the Fonzie trick will only result in a large black-and-blue mark on your hand. Hint: The time to stop banging on it and give up is when you're putting dents in the hood.

RAY: Here's the good news, Steve: A bulb for this car costs less than 10 bucks. And you easily can change it yourself.

TOM: So, pound away as long as you want. But sometime before you actually break your hand, I'd recommend just replacing the bulb instead.