Weasel, do I need a new regulator or just the dog driver (part number # 51353448645)? BTW, does anyone have a picture of the dog driver?
Thanks

It's going to end up being the regulator itself. The part that the window bolts to breaks loose from the cable usually, or the plastic pulley the motor drives get messed up and cause the cable to unwind and wrap around it.

If you want to make sure, just pull the panel off and give it a look. Be careful not to damage the foam vapor barrier, it needs to be carefully removed and reinstalled to prevent water ingress when it rains.

Thanks! I will take the panel off and snap some pics.

Guys, I have good news: I was able to repair the rear window - it works like a charm now.
A DIY can be found at http://www.kenza.biz/Rear-window-repair.doc . Please let me know if anyone have questions.