The subject says it all. The sound from the earpiece during a call is very distorted, to the point it is hard to understand the other person. They say they can hear me fine. The sound is fine when I switch to the loudspeaker or through my car speakers via Bluetooth. It is literally just the earpiece.

I searched TJC and found this post from 2014 which describes exactly my problem. One answer suggests to clean the earpiece. I tried as much as I could but it made no difference, probably because I only managed to do what the poster did and clean only the parts I could reach. I could not reach the actual earpiece because it is burred under the main PCB and I could not figure out how to take it out.

Has anyone had a similar issue that they managed to fix? Is it even worth trying? If so, how can I remove the PCB without breaking something? It gives quite some resistance to removal.