Time to gear up Mr. Peabody’s WABAC machine for another stroll into the garden of Baby Boomer nostalgia, this time in the form of a new book by Mark Rosenman and Howie Karpin called “Down on the Korner.”

The subject, as you might have gleaned from the spelling, is “Kiner’s Korner,” the late, beloved postgame show hosted by the late, beloved Mets announcer Ralph Kiner.

The idea for the book literally tumbled out of a wall at Rosenman’s house in Commack shortly after Kiner died in early 2014 at age 91.

Rosenman had been upgrading the flooring in preparation to sell and was having a wall unit removed when he heard a “loud thud, and then more thuds.”

There on the floor was a pile of Betamax tapes from the 1980s he had forgotten were there, and the first one he picked up was labeled “Opening Day, 1985.”

After he uncovered an old Betamax deck, he fast-forwarded through the game, famous for Gary Carter’s game-winning home run in his Mets debut. But what he really wanted to see was the postgame show.

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“It was, ‘Please be there, please be there, please be there,’ ” Rosenman said.

And there it was, Kiner and Carter, at last able to be preserved for eternity.

That incident also motivated the book. “There have been books written on Ralph Kiner,” Rosenman said, “but no books written on ‘Kiner’s Korner.’ ’’

Now there is. (Full disclosure: I am one of several sports media reporters/columnists quoted in it.)

The book has an endearingly unpolished, unfocused tone, much like Kiner’s show, and some stories are repetitive.

But there are plenty of nuggets to be mined in an oral history featuring the best of the 65 to 70 players the authors interviewed about their “Kiner’s Korner” memories.

What comes through is how much respect the players had for Kiner, and how much reverence some had for the show itself, especially those who grew up with it in the New York area.

Ricky Horton, a former pitcher for the Cardinals from Hyde Park, recalled following an exercise regimen Tom Seaver had discussed on the show.

“As a kid, I was hanging on every word,” he says in the book, “but I really pictured myself not just being the star of a really big game, but being on that show to culminate it and talk about it as it truly was a dream of mine.”

Horton recalled being crushed when he more than held his own against Dwight Gooden in the Mets’ home opener on April 14, 1986, a game the Cardinals won in 13 innings.

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Afterward he got stuck doing a long St. Louis radio interview and was unable to respond in time to an invitation to go on with Kiner, who settled for Ozzie Smith instead.

“On the ride home, I kept thinking as awesome as this day was, I still missed out on something that mattered to me in a way that people quite did not understand,” Horton says.

The next season, Mets announcer Tim McCarver, having heard about Horton’s disappointment, had him record a special introduction to the show on the field before a game.

“I am so grateful to Tim for that,” he says in the book. “I can always say I was on ‘Kiner’s Korner,’ which was a bucket list dream fulfilled.”

That is a long way of explaining the appeal the no-frills show had for players and fans from an era before there were elaborate, extensive postgame shows on fancy sets, complete with hosts, analysts and reporters.

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The archive of existing “Kiner’s Korner” shows is slim, perhaps a total of three dozen or so. Rosenman has the 10 or 11 that were hidden in his wall, which he has posted on YouTube.

There are audio recordings of shows from the 1960s from a collector named Phil Gries, some of which are quoted in the book. Another collector, Joe Barbarisi, had some old shows on videotape.

But mostly, “Kiner’s Korner” exists in the memories of fans and players, including its theme, “The Flag of Victory Polka” by Ira Ironstrings, aka Alvino Rey, aka Alvino McBurney.

It was released in 1962, the same year as the Mets, and “Kiner’s Korner.”