This solution below shows which particular components needs to be check for hardware repair troubleshooting.
Hints for repair:
Check the earpiece speaker first by using a multimeter set to X1, you can hear a crackling sound when hitting the two terminal with the tester's probes.
Clean the earpiece terminal contact pads on the C1-01 PCB board.
If the earpiece speaker is working and the contact pads is already cleaned but still the problem still exist. You may used the solution above and check those highlighted components, it is composed of filter coils, an ESD protection resistors and bypass capacitors.
Nokia C1-01 Earpiece Speaker Solution