[salguod]

Well, I figured out at least part of the problem. The plastic part at the base of the LH control rail is broken.

That's all I can see broken, but the reason that it's scraping is that the inner panel isn't tracking properly. When the sunroof retracts and is then closed, the inner panel slips and doesn't close all the way. The next time it retracts, the inner panel is misaligned (the tab in the one image needs to drop into the slot in the inner panel and it can't) and the outer can't drop all the way, so it scrapes on the inside of the roof.

The first step is replacing the rail and the slider at it's base. Then I can see if that was causing the misalignment. Hopefully that's the case, because where the inner attaches to the cable system is beck inside the roof and not accessible without dropping the cassette.