All good over here working with Projet printers currently; in a weird way it's strangely comforting to see that even $60k+ printers suffer from poor design decisions.
I have been keeping some distance from the whole situation, partly out of bitterness, and partly of fear that I'd say something stupid. But with Solidoodle suspending operations I feel a bit more comfortable crawling out of the woodwork. I know there are still plenty of people out there with SD printers so I hope I can help any way I can.
@scramjet I actually have a few more ideas. It may not be the extruder fan! Your comment about the fans inside reminded me that there's a fan on the bottom of the printer, accessed by removing the motherboard panel, that just happens to be right next to the birds nest of wires connected to the motherboard and sometimes the fan blades hit some of the wires that drift over there. Also the wire on that particular fan is super short, so make sure it's firmly connected to the mobo.
You can also try checking the fan in the back, about halfway up the height of the printer. But really, these are some cheap ass fans and I wouldn't be surprised if they were just bad.