Despite its strong score by composer Jerry Herman, “Mack & Mabel” is virtually a textbook example of the big Broadway flop. Though the subject matter might seem perfect-a roller-coaster romance between two silent screen legends, studio boss Mack Sennett and Mabel Normand, his starring comedienne-the 1974 musical abruptly closed after only 66 performances.

Everyone involved gave different reasons for this legendary Broadway failure. Some said the 30-year difference in age between stars Robert Preston and Bernadette Peters was too hard for audiences to swallow. Others blamed the bleak, “bummer” of a book by Michael Stewart. Mack was an unfaithful workaholic; Mabel was an addict who died young.

Yet despite its obvious shortcomings this failed show continued to enjoy major cult status. Various concert versions over the years showcased Herman’s music, which many consider his best score. The plentiful up-tempo numbers not only effectively tell the story but also reflect the frenetic energy of the early film industry. There are also some great ballads like “Time Heals Everything.”

We’re fortunate that director and choreographer Kevin Bellie and Circle Theatre make it their business to frequently mount such famous flops. It’s thrilling to witness this show come alive with flair and insight. There are non-stop, fast-paced episodes with spectacular production numbers. The infectiously melodic songs are all toe-tappers. But the book, alas, still poses problems.

The new Circle production uses an updated script that removes the original downbeat ending and replaces it with a rather vague, ambiguous one. I’m not sure this is an improvement. Frankly, audiences have grown up a lot in the last three and a half decades. I think now we might be able to handle a dark ending. Though I hate the term, we’d rather have closure, no matter how downbeat.

Yet “Mack & Mabel” definitely captures the spunk and madness of slapstick film-making. Sennett, the innovative “King of Comedy,” was truly making up his art as he went along.

Cat Davis plays Mabel Normand, a cutie pie who supposedly lights up a room, but like so many aspects of this story, we seldom witness this happening. You just have to buy it because they say so. It’s never clear just why or how Mabel Normand became such a major star-what made her stand out among the other “Hundreds of Beautiful Girls”? Neither her character nor Sennett’s are particularly warm or loveable.

During the shooting of one of Sennett’s slapstick “two-reelers,” Brooklyn delicatessen delivery girl Normand shows up with someone’s sandwich order. Mack immediately thrusts Mabel into the movies. Even she can’t quite believe it, as she sings: “Hold your tongue and hold your snickers/For the new enchantress of the flickers/Is that plain little Nellie/The kid from the deli?” Virtually overnight Mabel is making her boss a lot of money by hurling custard pies and taking pratfalls.

The show is paced like a runaway locomotive, usually a plus for musicals, yet this time, since the plot spans decades and we never get too close to the title couple, it feels like there are gaps in the story. Especially problematic is that we have to make such huge leaps of faith to buy the relationship between Mack and Mabel. There’s not much obvious chemistry there. It’s hard for a love story to be heart-wrenching when it has never touched your heart in the first place.

Jon Steinhagen, the playwright-composer whose new musical “The Teapot Scandals” is currently enjoying a successful run at Porchlight Music Theatre, plays silent movie mogul Mack Sennett. He’s so abrasive and cold it’s unclear why Mabel is smitten with her boss. He never openly declares his love for her. Dump him, honey, I found myself thinking.

But Steinhagen is convincing as this driven director and is touching as he sings the haunting ballad, “I Won’t Send Roses,” that lays out his rules to his leading lady: “Should I love you, you would be/The last to know./I won’t send roses/And roses suit you so.”

Herman’s score includes “When Mabel Comes In the Room,” his obligatory welcome-back-diva number (as in his ’60s hits, “Hello Dolly!” and “Mame”.)

There’s a fun character named Lottie (Brigitte Ditmars), a hoofer in the early “talkies” (a la “Singin’ in the Rain”). But we don’t care much about her even though she has two important songs. One of them, “Tap Your Troubles Away,” a raucous razzle-dazzle number that comes out of nowhere, remained trapped in my head for days:

“Tap your troubles away/You’re sued for divorce/Your brother gets locked up/Tap your troubles away/You’re fat as a horse/And find that you’re knocked up/Just tap, tap, tap your troubles away!”

Choreographer Bellie has devised some eye-catching effects and dance sequences.

One amazing, on-going special effect that’s especially effective is an assortment of rear-projected vintage silent film clips from the ‘teens and ’20s that’s seamlessly interspersed with new simulated black-and-white footage created by Bellie and Bob Knuth in the Keystone Studio style. These snippets of cinematic gold are wonderful, but the gimmick sometimes functions as Barroom TV Syndrome, pulling your attention away from the live action in front of you to focus on the fake flickers.

Peter Rasey plays the irrepressible Fatty Arbuckle, Mabel’s comedy co-star who, like Mabel, was the victim of “trial by headline” following a Hollywood scandal in the ’20s. Andy Baldeschwiler looks great as “serious” director William Desmond Taylor, with whom Mabel has a fling. But since we never get to warm up to Taylor, it’s hard to feel much when he’s murdered. But the sensationalistic publicity first tainted, then snuffed out Mabel’s film career.

Peter J. Storms is the music director. Beth Scheible is stage manager.

The Circle production is definitely worth experiencing, but perhaps “Mack & Mabel” ultimately does work best as a concert musical.