Astonishingly, despite my ability to make the wrong decision at every opportunity, moving the drives over to the old caddies and enclosure worked!
The raid set instantly showed up (degraded with just one drive down). I swapped in your new drive, set it to hot spare, and it’s now rebuilding.
Thanks so much for your help. Always a calm voice in times of panic. It’s seriously appreciated.
All the best,
James.