They're just gluing a plastic switch activator -- the switch
itself isn't being touched in any way.

If there's room, I'd use heat shrink around the repaired shaft.

Just Another Theremin Fan wrote:
The switch is a safety device and should be replaced ONLY
with an approved one.

The people advising super glue and worse are dangerous
****s who shouldn't be anywhere near electrical equipment.

Of course if you want your house burnt down then go ahead....