Re: Sensor damage?
 

Well, looks like it was sensor damage rather than a simple clean. Haven't worked out yet whether insurance would cover it; if they do, then I might as well get it fixed.

Unexpected advantage of using a DSLR -- the camera is very eBayable, even without repair. After all, those little dots might kill any commercial video application, but, for photographs, you can batch-automate a Photoshop content fill to get rid of them.

Re: Sensor damage?
 

You might as well put a buy it now up on eBay ... if it sells, it sells. Otherwise get it repaired.