Left I/O board MacBook Pro 17"
Was getting a mechanical farting sound from my speakers every time the computer attempted to play audio. Embarrassing to say the least. Speakers disappeared from the "sounds" output profile, and all attempts at software or setting modification didn't help. No audio from headphone jacks either, and intermittent red light from port.
Followed posted repair guide exactly. The directions were flawless. Repair was successful.
In one or two places, the torx or phillips screws were of slightly different lengths even though they looked pretty much the same at first glance. Separate screws by step number in small containers or folded up in paper to keep them straight. Be careful in some locations of the (outer) case as there are some holes into which the screws fit almost perfectly, but they are not the correct places for the screws.
Phillips #00 Screwdriver
TR6 Torx Security Screwdriver
MacBook Pro 17" (Model A1229) Left I/O Board