Play it again, and again ...

Sometimes he forgets his lines.

It doesn’t happen often, but now and again George Lee Andrews will be singing or gamboling onstage at the Majestic Theatre, in front of a crowd of 1,600, and he will simply go blank. He’ll hunt, but it’s like the words are dressed in camouflage and hiding in the jungle.

“Oh, I’ve had some legendary moments,” chuckles Andrews, sitting in his dressing room one recent evening.

It’s the kind of flop-sweat terror every Broadway actor knows. But Andrews is not just any Broadway actor. He’s a cast member of “The Phantom of the Opera,” a musical that is less than a week away from setting a record as the longest-running production in Broadway history. After a special gala performance on Monday, “Phantom” will have been performed 7,486 times, one more than “Cats,” which closed five years ago. (“The Fantasticks,” which was staged more than 17,000 times, doesn’t count in this derby because it was an off-Broadway show, which means it ran in a theater with fewer than 500 seats.)

Here’s the staggering part: Andrews has been in the show, continuously, since opening night. When “Cats” closed there wasn’t a single actor who’d been in the production from the start. “Phantom” has three: Andrews, Richard Warren Pugh and Mary Leigh Stahl. Excluding vacation and sick leave, this trio has been rehashing the same story about the same half-masked freak in the same hokey extravaganza, eight times a week, for 18 consecutive years.

Imagine it. Eighteen years of Andrew Lloyd Webber’s NutraSweet score, a hybrid that suggests Puccini as rendered by A Flock of Seagulls. Plus numbingly sentimental lyrics, courtesy of Charles Hart and Richard Stilgoe. It’s the sort of punishment that the Geneva Conventions were supposed to ban, isn’t it? But the math doesn’t lie. Tally up the actual stage time, excluding rehearsals, and each of these three actors has spent 750 24-hour days, more than two years of their respective lives, performing “Phantom.”

“People ask me if I get bored,” says Andrews, who seems the opposite of aggrieved and rarely stops smiling. “That’s not really an issue for me.”

Everybody knew “The Phantom of the Opera,” an adaptation of the novel by Gaston Leroux, would be a hit when it opened here in 1988. The original, in London, was a phenomenon, and the show opened in Manhattan with a record $18 million in advance ticket sales.

Reviews were generally positive, and the production eventually won seven Tony Awards, including best musical.

But there are hits and there are Hits. With worldwide box office receipts of more than $3.2 billion, “Phantom” is now the highest-grossing entertainment venture in history -- dwarfing the $1.8 billion earned by “Titanic.” According to the show’s public relations office, more than 80 million people around the world have seen “Phantom,” either in one of the six permanent productions scattered from Budapest to Tokyo or in the U.S. road version, which has for years been crisscrossing the country. Another version is set to open at the Venetian Hotel in Las Vegas.

The show’s director, Harold Prince, thinks the atmosphere of fantasy is key to its success.

“It’s far removed from the lives that people live outside the theater,” he said by phone last week. “It’s like a kid coming to a magic show. Everyone leaves their troubles behind, and you enter this world that is mysterious and glamorous and exotic.”

The movie version, released in 2004, certainly helped. It was a flop, but the advertising campaign used the same imagery and music. Like everything else on Broadway, the show took a beating after 9/11 crushed the tourism business. But “we just checked the grosses and 2005 will be our best year ever,” says Alan Wasser, who manages the production.

The producers have built their latest ad campaign, billed as “Remember Your First Time,” on the assumption that everyone on Earth has sat through it already, and probably more than once. Hard-core Phans -- as they call themselves, naturally -- have been to the show dozens and sometimes hundreds of times and swamp chat rooms with minutiae and memories.

The Majestic’s dressing room area feels surprisingly like a cabin on a submarine. Everything is packed in close, every inch of space is used, and before a show, everyone is scurrying to do a job they seem to know by heart. You hear the tra-la-las of performers warming up. A voice on a loudspeaker booms a countdown to curtain time and occasionally the name of an actor.

“If you don’t sign in, they start calling your name on the PA,” Andrews says in his dressing room. “Then they’ll call your cellphone. That happens to me when I’m at Starbucks.”

Andrews moved to New York City more than 30 years ago from Milwaukee, starting his Broadway career in 1973 with “Jacques Brel Is Alive and Well and Living in Paris.” For the last past five years, he’s played Monsieur Andre, his third part over these past 18 years.

Andrews appears to be the unofficial mayor of backstage Phantomville, and its historian, too. He has kept track of the actors who pirouetted through the play and then moved on -- asking each for a head shot.”I think there are something like 260 pictures down there now,” Andrews says.

According to the production office, come Monday, the Phantom at the Majestic will have been shot at 14,972 times. Some 1.4 million gallons of shot powder, needed for an assortment of flash pots, will have been burned. And if you laid out end to end the pages of Playbills handed to audience members since opening night, you’d have 43,105 miles of paper, enough almost to circle the globe twice.

“We counted, and it’s over 700 steps per night,” says Mary Leigh Stahl, who has the distinction of playing the same parts every night for the 18-year run. “That includes three trips to the dressing room, which is on the fifth floor.”

For Stahl and the other 18-year veterans of the show, “Phantom” has provided a lifestyle that is all but unheard of in the theater world.

“I don’t think I’d still be in New York if I hadn’t gotten ‘Phantom,’ ” Stahl said. “This isn’t an easy business, especially for women. I feel like I hit the lottery.”

A sense of gratitude, not to mention decorum, might explain why you won’t hear a primal scream of restive anguish from Andrews, Pugh or Stahl.

All three politely deflect every version of the question, Hey, isn’t this gig driving you bonkers? “It’s work, and this show has been amazing to me,” says Pugh, who has played four parts during his tenure.

The challenge is to locate the ideal mental state to recite the same words for the 7,000th time. Total concentration, weirdly enough, has its perils.

If you’ve ever focused hard on a mundane task -- like walking down a flight of stairs, for instance -- and screwed up as a result, you know why. In the days after Andrews botches a line, he tends to over-think his dialogue in the shows that follow.

“You’re running scared for a few performances,” he says. “You’re thinking three steps ahead, which isn’t good.”

But letting your mind wander is worse. Stahl says she’s caught herself thinking about a house she is about to remodel.

“I’m going to retire in eight months, to this place in Alabama,” she says. “So I’ll be in the middle of the show thinking, ‘Maybe I should get the kitchen floor redone.’ ”

The other challenge is trying to forget work when you’re not punched in. That can be tricky, given that the original cast recording of “Phantom” spent more than six years on the Billboard pop album charts.

Pugh was honeymooning in Bermuda years ago, and piped over the loudspeakers at a restaurant came “Music of the Night.”

“It was the first time I’d been away from the show in a couple years,” he says. “I told the waiter, ‘It’s a lovely song. But here’s $10. Play something else.’ ”