He then moved the mouse about some more, saw the cursor was doing the right thing, said "that fixed it" and left with a sense of achievement.
If I'd had an audience when I gingerly played with my first mouse, I might easily have done the same. As it was, it just took a couple of simple moves to figure out which way to hold it.
This thread is clearly the place to post the essential helpdesk video: https://www.youtube.com/watch?v=j_p3TYXmJFk