I just realized the audio output jack on my MBP isn't working right, it produces a crackle loud enough to blast your ears and makes connecting an external speaker impossible. Up to now I had iTunes running on another Mac (legacy) so i hadn't even tried using the jack and didn't know about this. Is it possible this can be fixed by opening up the MBP and tightening the jack or something, or is ths something I'd have to have Apple do? The closest Apple store is a good hour away by train and then there is a fair walk from the station too. So I would much rather try to fix it myself if it is possible.