Hi @chedley ,
The voice inlet hole to the microphone may be blocked with lint etc. Try using a vacuum cleaner and see if this clears the obstruction.
DO NOT use a pin or probe to try and clear it as you may damage the microphone which is directly behind it.
Hi @chedley ,
No I don't sorry.
This is the best that I can find.
Here is a video that shows the teardown of a LG V20.
Here is an image taken from the showing showing the mic (I think).
(click on image to enlarge for better viewing).
I can't see any "flex cable" in the video/image for the mic so am wondering if the link I posted earlier was for the correct one. (I did say "if this is the one" hoping that you could tell when you opened the phone). You may have a better view when you've dis-assembled the phone to that point.