There are few pipe organs in the world that have a nickname, a feminine pronoun and a Facebook fan page. The Hazel Wright organ — just “Hazel,” to her admirers — was removed piece by piece in 2013 from Christ Cathedral’s shimmering sanctuary in Southern California’s Orange County, and shipped to Italy for repair. At the time, the fifth-largest pipe organ in the world was suffering from an infestation of bugs. Its pipes were melted, its trumpets corroded. Nearly a decade and $3 million later, Hazel is back in the fully remodeled sanctuary, and heavenly chords from her pipes once...