I have a factory installed rcd 510 with 9w7 bluetooth module in a 2010 Tiguan, I purchased used. For some reason the microphone isn't working. All the functions except this work. My phone connects, phone book appears, streaming works etc. But whenever a call is placed or received no one can hear me. Any clue why this is happening? Could the microphone have gone bad? I took the microphone out to inspect it and it looks undamaged. I have searched countless forums to no avail for a solution