Thanks to Zoey for quickly helping to resolve an issue with a dead 8KX headset … the firmware needed to be re-flashed.
Also, thanks to @Akuma540 and @MReis for suggestions on how to successfully resolve controller pairing issues. I got new Index controlllers to replace old ones (joystick drift), and could not pair them. After a couple of hours, I finally found the topic where the solution lay:
Deinstall LHR and Pimax P2B under windows settings/Devices and replug the USB
Removing all USB Devices in Steam VR Developer Settings, unpluging the HMD and Rebooting, re pluging and then Pairing