When I mentioned using a can of air, I meant through the front slot--not by opening it up.
I have to do this on my Xbox for this very same reason, and it always solves the problem of a noisy drive. But of course I'm not so protective of my xbox since I could easily install a new dvd-rom.
I would recommend using something to keep the slot cover opened (like part of a pen cap) while you blow some air in there from a foot or so away. If your planning on sending it to nintendo if nothing else works, this would be pretty much your only option without being invasive.