Hello :) I found myself in this situation as well :) I had even tested the mic before taping everything up - but there I went and covered the mic with tape as well when putting everything back together :( . Just incase .... wished to share that I found an incredibly small ( no bigger than 2 cm) usb mic from amazon for 7$. When you turn up the "gain" in system preferences it sounds exactly ( 90%) like the original iMac mic if you wish not to re-open the iMac ... Thank you all again for sharing this find and story !