Suddenly very thin sound.

This is an old post but thought I’d give it a go. I had the same thing. Considered the mic lost so I investigated. I found that a piece of the grey foam circle on the capsule (so inside the mic after you remove the spherical guard) had lodged itself in one of the holes in the membrane guard. The foam was deteriorating and getting stuck between the membrane and the black plastic cover. I carefully cleaned it with a can of electronics cleaner and a careful shot of compressed air, being extremely careful to not damage the thin transparent membrane. The mic was as good as new. I did not replace the small foam disc but I don’t notice any difference. Not sure if this helps but mine is fine now. Still working fine 3 months later. Good luck!