The gold wire is hidden inside the red-green wire. Unwind the red-green to find it. The gold is the mic, the red-green is the mic ground. If you use the original jack (cut away the moulded on white plastic) you can use a multimeter to find the mic connection which is on the other side of the ground connection. Thanks for the page. Good luck

Brilliant article. I just replaced the original 120 GB HD with a Toshiba 500 GB HD after the original started to fail after nine years. It has lasted well and still does the job to take to a cafe so why not keep it going. Agree with the advice above to place the screws down in order. Also to not bother with step 11 if you can still disconnect the drive. And as above check that the breather hole is not covered. On the new Toshiba HDs the hole can be just at the place you would stick the ribbon back down. Thanks iFixit.