It’s one of the oldest clichés there is, but sometimes, it’s true, you can get too much of a good thing.

An example is now unfolding on Broadway, where “Gutenberg! The Musical!” opened this week. Originally conceived as something of a lark by the talented stage and screenwriters Scott Brown and Anthony King — who performed it themselves at London before recruiting more experienced actors for an off-Broadway production back in 2006 — the piece follows a pair of wanna-be musical theater creators who put together a show about, yes, the German inventor known for giving the world the printing press.

If that sounds like a flimsy premise for a two-act musical, that’s the point; the rub is that, well, Messrs. Brown and King have devoted a two-act musical to making that point. It’s a credit to their skills that, 17 years ago, “Gutenberg” attracted the attention of the rising director Alex Timbers, who is now one of the busiest and hottest artists in his field, and who is helming the show’s Broadway premiere as well.

Even more conspicuously, the new production of “Gutenberg” marks the return to Broadway of Josh Gad and Andrew Rannells, who rocketed to fame more than a decade ago as the original stars of “The Book of Mormon.” The actors had apparently been looking for a vehicle in which to join forces again, and it would be hard to imagine a better one than this romp, for which Messrs. Brown and King, who previously collaborated on the book for the musical adaptation of the film “Beetlejuice” (also directed by Mr. Timbers), have also written music and lyrics.

It would be a bit of a stretch, mind you, to characterize the duo’s contributions in this arena as a score. Notably, the playbill for “Gutenberg” does not list any musical numbers; Bud and Doug, the nursing home workers respectively played by Messrs. Gad and Rannells, are not meant to be serious or even competent composers. They’re just two guys with a dream, and enough money — after Bud squanders a small inheritance and Doug sells his parents’ home — to rent a Broadway theater for one night.

With no cash left for a proper reading, the co-workers turned collaborators are left to play all the roles themselves, with only a bunch of labeled baseball caps as props. Juggling characters ranging from a villainous monk to a sweet-voiced little girl who just happens to be a raging antisemite — along with the virtuous Johannes Gutenberg himself, of course — both stars make full use of their considerable comedic gifts, while exhibiting an infectious camaraderie.

Between the characters’ dialogue and their songs, both of which nod wittily to musical theater tropes, Doug defines relevant terms for the audience. “A metaphor is when you say one thing, and mean something else, but you’re not lying,” he chirps, then later explains, “A motif is when you use the same music over and over again — but it’s not lazy.”

Such lecturing is part of the joke, as Bud and Doug are ostensibly showcasing their work to an informed crowd. “Chances are, if you don’t know the person sitting beside you — they’re probably a Broadway producer,” Doug notes excitedly, early on.

While you needn’t be a musical theater aficionado of any sort to appreciate and enjoy the tremendous skill and affection that the entire “Gutenberg” team brings to the subject matter, the show would likely have worked better as a one-act offering — which it was, in fact, when Messrs. Brown and King first hatched it roughly 20 years ago, as a 45-minute skit.

I would have happily sat twice as long as that through a production of this quality, and at two hours with a 15-minute intermission, the musical really only needs a short trim, including the break. To borrow another platitude, a little change can make a big difference.