Hie Friends
I came up with a good news
My qc20i right side earphone was making craking sound while playback and when I on the noise canceling button it not canceling full from right side , m very music addicted and I prefer only quality in Meanwhile I was so depressed and researched all over internet about this problem but I got no solving way then I research on earphone mechanism then I got an idea THEN IT WORKS PERFECT that is
Remove your earbud ( white bud ) which side is not working then clean it with tooth brush carefully then blow air with mouth in to the earphone tightly and make sure that air going through other side ( metal mesh ) of the ear phone then repeat from mesh side and let the air from budside way , repeat that 2 times and then connect the earphone to your device and check
Hope it will work
Worked for me
All the best