Recently I made the mistake of lowering a rear window while a window blind was stuck to it. The suction cup disappeared down into the door, so I went to raise the window, at which point it all went horribly wrong! There was a sound like breaking glass, and the window got stuck. Fortunately it transpired that no glass was broken, but the window regulator was, and that needed replacing. So the most obvious question is, what the hell is a window regulator?

So in the above photo, the top item is a replacement window regulator, and the lower item is the broken one I removed. There’s a steel cable that’s wrapped around the central drum, and that had burst off the drum, and the noise I’d heard was it flipping around the drum and hitting the window glass.

Replacing the item isn’t especially hard. I found a good guide here: http://www.bmwgm5.com/Rear_Window_Regulator.htm

The part is BMW B51.35.8.212.099 which currently retails at £75.84 ex VAT.