Travel Technology - Screeching problem with Plane Quiet NC headphones

I have a screeching problem with my Plane Quiet noise cancelling headphones.

It is a high pitch screeching sound when I move my head around or chew or whatever. I use them at the fitness center so this is not working.
I replaced them with a new set and developed the same problem a month later. (OK, I know, so stop buying them).
It is purely mechanical as I get the screech (only in the right headphone) whether the noise cancellation is on or not and whether I have music playing or not. It sounds like something is scratching the diaphram. At first I thought it was old-person-ear-hair but I have ruled that out. What I ended up doing was lubricating joints on that side with dry graphite powder lubricant. It seems to help for a few days but the problem returns.
I tried emailing Plane Quiet folks but no answer.

Anyone with similar problems or a resolution?

it might be loose wires inside the head phone... (if you think it sounds
like someone scratching as you move)

sometimes it might be like feedback whistle..... but you'll know if you hear one.

whats the make and model? this way we know what to avoid.

Thanks,
The model is the NC 6.
But it appears to be entirely mechanical. The scratching is present with no power and no signal.

Seems to me like a missing washer in the articulated joints. I think I can feel the vibration in the headgear.

Strange how I got 2 bad ones.

I'll be in Ashland, OR in September and I'll have the ProTravelGear guys check them out.

Sounds very weird. Good luck!