Long ago--in a more steampunk age--there was a rich factory owner whose factories were sitting silent.  The boiler that powered all of them was broken. He hired expert after expert, consultants and scientists with rooms full of scientific-looking testing equipment. None of them could figure out why the boiler wouldn't hold any pressure.

One day, as the factory owner was getting very desperate, an unassuming boilerman with a very small toolbox came to his office.

"I hear you're having trouble with your boiler," the boilerman said.

"I am," the owner replied, "but all of the best boilermen have been through here and none of them have been any help. What makes you any different?"

"Probably nothing," the boilerman said. "How about I take a look at it. If I can't fix it, you've lost nothing."

The factory owner thought for a moment, sighed his resignation, and led him to the boiler. The man looked at it for a moment and opened his bag to reveal a small rubber mallet, a piece of chalk, and nothing else.

"That's it? Where is all of your equipment?" the factory owner laughed.

The boilerman nodded, smiled, and marked a small 'X' on the side of the boiler. He picked up the mallet and tapped on the chalk mark, and the boiler roared to life. The owner was surprised but very excited. 

A few days later, he got a bill from the boilerman for $1000. He called the boilerman into his office.

"What's this?" he shouted. "All you did was tap it with your little hammer! I'd like for you to itemize this bill for me, please."

The boilerman returned with another bill. The owner read it.

"For tapping with the mallet, $15. For knowing where to tap, $985."