That is the EXACT deal I had.. this was 1.5 years ago, so I now have more data..
I tried, knowing I would be screwed again, to open it and it won't open at all, now.. it grinds, and sounds awful when I press the switch, now (but, no movement..) The plastic gear inside melts from heat transfer from the sun on the roof, etc... Only fix is either replacing just that gear on your OWN (one guy is making metal fabbed ones, now...) OR replacing the entire unit at a cost of MORE than a clutch w/labor!
Get used to cracking windows, instead...
Ray