I spent an evening performing unexpected surgery on my Xbox 360. When I put a game in, the drive made the most horrible grinding noise. On top of that, the drive would not stay closed. The tray would almost always eject seconds after being closed. Research led me to conclude that the rare earth magnet that is part of the disc clamp had probably become unglued. Since my initial warranty has long since expired and the red ring of death warranty only has another year, I decided to crack the case myself.
It's not worth going through the details, but I did find two useful videos. The first is an overview of the problem. The second is a good tutorial on opening the 360's case. I used some Zap-A-Gap brand contact adhesive that I had laying around to actually reattach the magnet.
I felt quite proud to have diagnosed, researched, and fixed the problem on my own (without sending my console to Microsoft for repairs). $100 plus shipping just to have some intern apply some glue is a little extreme. So many people have had this problem that YouTube videos just refer to it as "the grinding noise problem." Either Hitachi (the drive manufacturer) just made a lousy drive, or Microsoft didn't correctly anticipate the effect that their game furnace would have on the glue that Hitachi used. I don't know who is to blame, but Microsoft should extend their warranty on the 360 to 3 years for all defects, not just those that cause the red LEDs to light up in a circular fashion. I don't expect my car to wear out in 2 years, and I use it every day. My game console shouldn't wear out, either.