Microphone not picking up sound

My Gear S microphone is not working

Everything else works great

I have reset the watch back to factory ...still didn't work

I have removed the microphone and reconnected it... still didn't work

I used the voice memo app to record and when i hit playback recording i hear crackling noise.

so i am pretty sure the microphone is bad

however i can not find the part number or the part and samsung is no help at all

any suggestions or if someone knows where i can buy the mic would be greatly appreciated

many thanks in advance