“What if we did ‘I Write the Songs’ in E?” Barry Manilow asked .

He was rehearsing , layered in black, in a nearly empty Lunt-Fontanne Theater in Midtown Manhattan, preparing for his fifth Broadway run since 1977, a hit-packed show called “Manilow Broadway.” The goal was to ease a transition from “Somewhere in the Night” to the Grammy-winning “ Songs.” His longtime music director, Ron Walters Jr., cued the band in the new key.

“That’s not bad,” Manilow said after hearing a few bars, meaning it wasn’t great either. They tried E flat. They tried F . Manilow’s manner was unhurried, even though — and this seems like it should cause some urgency — the show was opening in two days and seven hours.

Manilow, who turned 76 this summer, walked gingerly offstage for a break, and a little later, he and the band worked on the introduction to Andrew Lloyd Webber’s “Memory,” a hit for Manilow in 1982. The trumpeter Charlie Peterson began the song with a solo, but it was too demure for Manilow’s taste. He asked Peterson to try again, with more drama: “Make us look at you,” he instructed, his Brooklyn accent apparent.