Dear Tom and Ray:

When I was a kid, my siblings and I loved to play with the power windows -- up a little, down a little, up some more, down some more, all the way up. Our elders always told us to cut it out because we'd wear out the switches. Now that I have kids of my own who love to do the same thing, I find it annoying, so I tell them to cut it out because they'll wear out the switches. But it makes me wonder -- can you really wear out power-window switches, or were my elders fibbing, just the way I am?

-- John

RAY: I don't think I'd worry too much about the switches, John.

TOM: No. Switches are cheap. It's the broken power-window motors and regulators that'll have you cursing the little rugrats.

RAY: All of those parts -- the switches, the motors and the window regulators (the mechanical pieces that actually move the glass up and down) -- have thousands of cycles in them. But not an infinite number.

TOM: So, let's say you have two kids, and we'll assume the little tykes are confined to the back seat. On a three-hour trip to Grandma's, let's say each kid works one rear window -- up and down, up and down, continuously. That's about 2,000 cycles right there. Or 4,000 round trip, if the kids aren't sleeping off candy comas after visiting Grandma.

RAY: If you make that trip once a year, within three years or so, you're going to need two window motors. And, depending on the car (sometimes you have to buy the regulator and the motor as one unit), they can cost anywhere between $200 and $500 per window!

TOM: So, you have two reasonable choices, John. One is to invent a coin-operated power-window mechanism. For a nickel or a dime, your kids will be able to raise or lower the window once, while contributing to their eventual repair.

RAY: Or you could simply limit the kids' playtime with the windows. You don't want to ruin all their fun, so give them a couple of minutes to play, and then when you start to smell smoke, tell them "Time's up," and deactivate their window switches (which you can do from the driver's control panel). Then, hopefully, they'll turn their destructive instincts to something less expensive, like opening and closing the ashtrays until their doors fall off.