I've had to replace a window channel once, for a 244 that had run over the felt/rubber/steel that it's made out of. Not too hard once the right things were greased. If the track is folded over anywhere, that may need to be done.

I've seen lots of 240s with the window separated from the steel channel that holds the glass. That just gets replaced, a good one shouldn't be more than $25 from a junkyard.

It could simply be a loose regulator. Remove the door handle and panel, and look for loose 10mm nuts holding the regulator to the door.

Last, the door could be cracked. This usually only happens to cars with power windows. The inner door skin will crack in the center of the top, and in one or two other spots where the top of the skin meets the window tracks. A quick patch with a MIG welder fixes this easily enough.

Good luck with it!
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Rob Bareiss, New London CT ::: Roterande Fläkt Och Drivremmar!