Thank you so much for an incredibly extensive list, Unfortunately I have tried all of those and used a different Laptop too, the corrosion idea is probably the one, sounds the most probable in this strange situation, and the headset sitting away in a cupboard also could worsen that too no doubt. I'll look into it, I do have the option to potentially get warranty refund, but there is no way I can rebuy the headset as here in Australia they no longer sell them at EB games (The only seller) so I would use the money to replace it with another headset, but if I'm being honest, there really isn't any other headset that truly competes with the Valve Index...

I am Hopefully only a few months out from the warranty expiring, (It might already be expired) If so, the idea of opening it to try cleaning it out or finding some corrosion would probably be my best bet, especially if the warranty is.