How to fix Google Nexus 6P microphone issues

My friends had been complaining that I sounded very distant or muffled when on calls on my  Google Nexus 6P. A quick google search later I found many posts with similar issues and various solutions that didn't work for me. Funny thing was that speaker calls were fine it was only when using the handset against my ear people complained.

On the first visual inspection, I couldn't see anything wrong with the mic. It wasn't until I put the mic under a strong magnifying glass and a bright LED light that found there are 2 very slender slots that were very clogged with gunk.

The 2 slots (each side of the mic bar located 5mm inwards from the right side of the mic area) are roughly 1 -2 mm across and could only be cleaned with a thin sewing needle. Once properly cleaned a few test calls showed that people thought I had bought a new phone.

I'll try to source some high res photos to explain what slots I mean.

If you find this article useful please leave me a comment.

Update: 16/12/2017 I am no longer able to take photos of my Nexus as it was returned for warranty and has since been swapped to a new phone. If someone could take a photo and leave it in the comments that would be great.

I still maintain that the nexus 6P was one of the best android phones I've had so far. only let down by a crap manufacturer warranty.