Replacing MacBook Air (Late 2008/Mid 2009) Audio Cable
The audio disappeared one day (everything: mike & line out, as well as speaker). It would reappear occasionally - rarely, actually - but it was impossible to get any hold on the reason. It wasn't software related, as it seemed. So I had to try the cable replacement.
The repair per se went smoothly; it's really not that difficult. Audio now works reliably (mike, line out, speaker, 100% available).
However, I noticed a highly pitched whistling noise when connecting the Air over line out to the HiFi amp. It's really high, not everybody hears it, but I do. This is bothering me a lot; not sure if it is related to the new cable or to cable crossings.
Some screws can be tight; it's hard to work without perfectly matching screwdriver. Also: pay attention when you put back the screws. Apple uses four different sizes here (iFixit has the sizes in the repair manual).