QuietControl 30 Degraded Noise Cancelling
I got my QuietControl 30 from someone who didn't need it anymore. It still worked great. Until yesterday, when I heard a loud, high pitched squeal in the left ear. I blew on the earbud, which resolved the issue. Afterwards, the noise cancelling felt like it was degraded. I've taken care of the headphones ever since I received them, but this is confusing. I can now hear things that are supposed to be filtered out, like keyboard clicking (which seems noticeably louder now), hand clapping, and even mouse clicking. I've already done the standard "check if the NC is all the way up", "restart the headphones", and all the other troubleshooting things. Does dust stuck in the outside holes affect ANC? Can I clean the mics that the ANC uses?
There is no damage to the device itself, and I handled it with care. What free options do I have?
P.S. this site was hard to navigate and I had to wait an awfully long time until I could post something here, I kept getting "registration pending" when I tried to log into the forums.