Failing window regulator. A little painful in the wallet, but an easy fix. ~$200 from Sunset Porsche in OR,
http://www.****************************************************.com/contact/order-parts-online/. These guys typically have the best prices for OEM parts. Good guys. Get to know them, but hopefully not too well.
The instructions on bombaydigital.com are quite good, though not perfect. Allocate a couple of hours to do the job slowly and methodically - if, like me, you're not super mechanically inclined. I repeat, easy job if you take your time.