Headset repair
I have not tried opening up the Lightspeed headsets. I will contact Lightspeed to see whether they can be repaired.
In the meantime, I tried a Lightspeed Zulu Pfx. To my surprise, the noise reduction was considerably poorer than the QFR's. The Pfx's don't have much clamping at all. No doubt that would make them more comfortable, but as a consequence, there was a lot of wind noise that leaked around the ear pads.
When the noise cancellation worked well in the PFX's, they were great. However, there was considerably popping and changes in the cancellation as I moved my head around in the cockpit. The build construction was fabulous, and I really wanted to like these headsets, but they needed to be flawless for the price. Unfortunately, they were not even close, and I returned them after 3 test flights.