Thanks Joe good overview. Ok I'll detach all cables first and reattach firmly.
I think that covers 80% of your post.
This is brand new 8TB for image data. (I just moved my doc data to the internal SSD)
The other brand new 8tB was for TM, so I could (tediously) swap those down the road. However, my backup system 1x day SD, and crashplan in cloud , is pretty good so probably could live with it... (the danger is you could lose work did during some day's work).... I think unlikely.. let see how much continues... take notes!)