The apprentice had been working in the workshop for almost two years. He was quick with his hands. He worked hard and was eager to prove himself.

One cold winter morning, an old utility arrived with a rattle somewhere beneath the bonnet.

The apprentice listened for only a few seconds.

"I know what that is."

He reached for his tools.

By lunchtime he had replaced two parts.

By mid-afternoon another part had been removed and replaced.

The sound was still there.

At that moment, the oldest mechanic in the workshop wandered over...