Audio Crackle and USB not working

Hi Guys

My Macbook air started to make these weird crackling noises (just like when you're inserting your headphones on high volume, the crackling you get from your aux touching the aux in) it happens a lot when i open sound files and videos but now it tends to crackle on start up and so on. I tried putting an earphone in, lowering the volume ... nothing works EXCEPT when i squeeze the frame of the macbook together on the location where the I/O board is based. Then it suddenly stops and everything is fine.

I think it's a loose connector or something but i'm not really sure (my tools arrive tomorrow so haven't yet opened it up). I'm hoping i don't have to replace my I/0 board but my usb port on the board isn't working either so ... maybe i should?!

Anyways, anyone out here that has known the problem?