Thanks Igor -
I followed all those steps, even number 7. I don't know if you noticed but step 8 is missing!
Anyway, I eventually made it to the point of chkdsk looking at and scan + fixing on my three drives. The one that I suspect was not working was in fact not, however, unlike Windows Explorer it was able to identify the disk name "Games".
Chkdsk encountered two "An unspecified error occurred" with code line.
It ended with "Failed to transfer logged messages to the event log with status 6."
The command line entry of /scannow /offbootdir=D:\ /offwinddir=D:\windows returned that the details of the logged events after successfully repairing corrupt files.
The restorehealth command had the operation complete successfully.
I rebooted and was again back in "Repairing your PC" loop.
I am now attempting to make a clean install of windows 10 off USB media installation.
At this moment I am attempting to remove extra partitions, but it is taking a lengthy amount of time to remove each one. So far I am hopeful that I will get to the installing windows stage.
The one amazing thing is how nearly every example on-line is NOT how my machine has acted. I feel I'm getting close to fully reinstalling Windows... but I still have my doubts.