Chosen Solution
I need to replace a microphone of a iMac 21.5" 4K Mid 2017. Since is an “non product numbered” for Apple, does anyone out there has a clue where I can find this item?
If your mic is garbled then you forgot to cut a notch in the adhesive tape so its not blocking the mic. If the mic is really not working you need Apple P/N 821-01020 which works in either the 2017 or 2019 4k systems.
