I have a three-year-old laptop with a rattling fan. It's not about dirt as I have already removed it and had it thoroughly cleaned up. After cleaning it, the rattling noise went away for a while, but now it's back again and is driving me mad.
The problem is the one depicted in this video, a tight back cover that somehow got closer contact to the fan. I know that's what's causing it because if I press the cover down using the USB cavity, the noise goes away.
The guy in the video says he put a "dent" between the back cover and the fan, I don't know what that is or how to do it, it's so frustrating.
https://www.youtube.com/watch?v=u44iwZCKR08