Cpu fan buzzing

[revolultrablue]

Hello, I recently dusted my computer and found later on while on the computer that a weird buzzing noise was coming from it. I removed the side and found when I stopped the cpu fan the buzzing stopped. The weird thing about the situation is that when i touch the side of the computer the buzzing from the cpu stops. Can anyone tell me why this is and is replacing the cpu fan the only way to get it to stop?

 

[revolultrablue]

Once I touch the side it stops pretty permanently but the next time I boot up it'll buzz again.

 

[revolultrablue]

Does anyone know how touching the side of the case could have anything to do with the cpu fan?