This solution simply shows the location of the particular components that need to check, trace or replace to solve microphone problem related issues on Nokia 5320.
Nokia 5320 Microphone, Mic or mouthpiece failure solution
1) Check or replace the microphone module
2) Ensure that the mic's terminals or pads is free from dirt or oxidation
3) Rework and trace the line paths from the audio IC (AVILMA).