As already posted by many Razer customers, the wireless USB adapter of my wonderful headset stopped its service. I tried to reestablish the coupling using the following applications:

NariDongleRecoveryTool_v1.02.00.exe

RazerNariPairingUtility_v1.01.00.exe

Nari_FirmwareUpdater_v15_r1.exe

But nothing worked. So, I guess it is just broken. Unfortunately, I cannot find a spare part. Maybe somone has an idea what I can do to resolve this issue - apart from buying another headset.