As fate would have it, the telescoping stalk on Mary’s helmet mirror broke off at the ball mount a few days after I assembled another spare mirror:
That’s the point where all the stress concentrates, but the stalk lasted almost exactly six years and didn’t owe me anything.
So I clamped the mirror+shaft+ball from a spare into the mount on her helmet, and she rode off as planned.
Once again being down to a single spare, I drilled a few more 10 mm balls:
Cleaning up the end of the broken shaft let me shove it into a drilled ball:
The insert and random screw came from the stub end of the broken shaft: ramming it into the cleaned-up end makes the job look Good Enough™.
Clamp the repaired stalk into the spare mount, drop the drilled balls & lathe fixture back in their bag, and maybe it’ll be another six years before they’re needed.
Life is good!
The Smell of Molten Projects in the Morning 
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