The bolt appears to have come out of the bell crank and the question is why that came out.

There's no proper record of the removal of the bell crank and its reinstallation,

They kept ringing the bell!

As I thought
about that, I had
to wonder: What will we
know better about tomorrow?
Who cares? Hindsight is useless.

It was a bolt from the blue.

The other guys have to crank it up a notch.