David Hufford is no ordinary repairman. His mission: get the music flowing again from a soggy, 63-year old pipe organ.

What happened to the old organ at St. Paul Evangelical Lutheran Church in Grosse Pointe Farms, Michigan? A flash flood happened to it. During a big storm, the church filled with more than seven feet of water. The flood damaged the church’s boiler, electrical system, elevator, and more.

“Just astounding,” says Mr. Hufford, thumbing through photos of the flooded church on his phone. But Mr. Hufford isn’t going to fix the boiler, electricity, or elevator. He’s a pipe organ expert. Not many people know how to do what he does. Right now, the city needs him.

“You might think that the pipe organ that sits high in the loft would be spared,” says Reverend Tim Pelc. He works at another flooded church nearby. “But the blower system, which supplies air to the bellows, is located in the basement.”

The system at Reverend Pelc’s church was “wiped out” by water. A piano now leads the hymns. Other area churches have the same problem. So does the nearly century-old Senate Theater in Detroit, home of a Mighty Wurlitzer organ.

Time to get to work! Mr. Hufford explains: A blower and other intricate parts of an organ are commonly installed in lower levels of a building. They serve as the “lungs of the organ.” He finds the organ’s wind reservoir. If this wooden box doesn’t work, the organ doesn’t work either.

Uh oh. The box is totally soaked. “It’s going to the dump,” says Mr. Hufford. “It’s done.”

The cost to fix the organ? About $12,000. The value of Mr. Hufford’s unique knowledge? Too much to guess.

Why? Pipe organs are not used as much as they used to be. But learning about how this complicated instrument works shows just how much knowledge and experience organ repair, building, and playing takes.