Thanks for the replies. No, I don't know for certain that the regulator is bad, but I had to take the panel off to try to figure out why it's stuck anyway, whether it's because the regulator broke, or a bolt holding the glass to the regulator just came loose (I'm hoping for the latter!). So, I have the panel completely off, but, as I said, I can't get the glass to budge. The odd thing is that it's stuck at the front, where most of the posts I've read on window problems have indicated the issues tend to be at the mounting point at the back.

I'll keep struggling with it to see if I can break (I didn't really just say that, did I...?) it loose. Then I'll be able to assess what's wrong.

By the way, on the E46, a common issue is that the clip that holds the window to the regulator tends to break, so people often repair them with zip ties. In fact, you can even reinforce the clip with a zip tie to help prevent future failure (I've done that on both front doors of my daughter's 04 325i). Is there something similar that can be done with the X5? Thanks.

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2003 X5 4.4i
1992 Porsche 968
2007 328i
2014 Subaru Forester XT