My issue was static noise on top of voice from caller rather than no sound at all.
My solution was to loosen the 2 screws, that hold the earpiece( https://d3nevzfk7ii3be.cloudfront.net/igi/IZYXyFLf3OoXZJSt.huge) in place. The screw that I believe made the most difference is the longer screw that tightens to tiny plastic spacer closest to the camera. I loosen that screw to almost half to 3/4 turn before it "pops" out. I made sure the earpiece is as level to the overall plane and not slanted (cos' by over tightening).
Put everything back together and it works perfect now!
https://d3nevzfk7ii3be.cloudfront.net/igi/UmppVqlwI23VGnDM
Hope this helps!