Thanks; yeah, I suspect it isn't my motor, since it drives the window down just fine, and I don't see why the motor would become too "weak" over time to drive the window back up. I suspect as you say that either there's some sort of obstruction on the tracks, or the regulator itself is binding for some reason. I should know by tomorrow; I'll keep everybody posted.

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