The proffered replacement had a difficult-to-print orientation:
Which Meshlab’s Manipulators Tool rotated by 90°:
And that printed without any drama (or support), at least after I sliced it to use a single perimeter thread that could cope with the arch:
Then a few pretty cable ties wrapped everything up in a decorative package:
And that’s that…
Memo to Self: Bang on the ␛ key to get out of whatever mode the Manipulators Tool gets wedged into.