I have an older 24" iMac that has an odd problem with the fan. From time to time, I can hear a grinding sound coming from the computer. I can press hard on the case and it will stop, and depending on how I tilt the screen up/down it will stop. Unfortunately, the point at which it grinds is the ideal angle for it to be viewable, so moving it is really not a good option. This leads me to believe it is loose, and it's wanting to fall down as when it's at an angle it stops. I don't see any way to fix this short of taking it apart, but any ideas about what it could be/fixes?