This is a very common problem.

The window regulator problem is usually discovered when one finds a window completely lowered without them using the switch. One of mine was discovered after I had parked the car and came out after several hours. The window was down. Another was discovered when I lowered it and it would not go back up. My third one was discovered when I heard a loud "pop" sound and the window dropped. This was while I was driving.

The only early detection might be if you hear a "pop" or other unnatural sound. I think I heard such a sound the night my third regulator failed. The window dropped about twenty minutes later.

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