I have located the source of the fault (in my case) that reports as a blink code 82h (which is believed to translate to "BGVSNS error" according to www available information).
The CPU daughter card (containing the PII processor and cache) that plugs into the base motherboard in the Tecra 8000 appears to be at fault.
Replacing the CPU daughter card with an available (tested) replacement restored the unit to full working order.
Subsequent testing of the original ("faulty") CPU daughter card in a known working Tecra 8000 resulted in the generation of the same error 82h blink code report on that machine.
Interestingly there are considerable differences in the construction of the two the CPU daughter cards in the two Tecra 8000 machines. One card appears to have a number of ICs, which may be cache, which are not present on the second card.
I hope the above information aids anyone with a similar problem in the future.
PS. I'm still interested if someone can can shed some light on where I can measure the BGVSNS voltage on the motherboard for the Tecra 8000.
(The Tecra 8000 will boot without both the Memory backup, and RTC batteries(with the obvious operating limitations)