The director Bartlett Sher has never, to my knowledge, pulled a sword from a stone, but for many musical theater fans his sublime revivals of classics such as “South Pacific,” “The King and I,” and “Fiddler on the Roof” have been similarly dazzling and inspiring feats. So it’s a little heartbreaking to report that his new production of “Camelot” is, not unlike King Arthur’s legendary Round Table in the show, a noble and thoughtful exercise that doesn’t succeed as brilliantly as one would have hoped. 

When introduced on Broadway in 1960, Alan Jay Lerner and Frederick Loewe’s adaptation of T.H. White’s “The Once and Future King” showcased the larger-than-life talents of Richard Burton, Julie Andrews, and Robert Goulet, respectively cast as Arthur, Queen Guenevere, and Lancelot du Lac, the dashing French knight who comes between the first two. If Lerner’s book wasn’t as sharp as his take on Shaw’s “Pygmalion” had been for “My Fair Lady” (which Mr. Sher also helmed, to wide praise), the “Camelot” score was equally ravishing and has proven just as enduring. Granted, nostalgia has also played a role in the show’s staying power; the very title is a romantic metaphor for the Kennedy administration. 

For this “Camelot,” Mr. Sher has teamed with the screenwriter and playwright Aaron Sorkin, previously his collaborator on an acclaimed adaptation of “To Kill A Mockingbird,” with the clear intent of emphasizing the musical’s broader and more current social and political relevance. While Mr. Sher spoke in a recent interview about wanting to explore our own national mythology, he and Mr. Sorkin, who’s best known as creator of “The West Wing,” apparently also wanted to make the musical’s mythological characters more accessible to contemporary Americans. 

To that end, Mr. Sorkin’s new book has abolished all supernatural elements and references to sorcery that existed in the original libretto. Arthur’s mentor, Merlyn — played here by a divinely witty Dakin Matthews, who doubles as the king’s elderly ally Pellinore — is no longer a magician, for instance, and the bewitching nymph Nimue has been eliminated altogether, along with her shimmering ballad, “Follow Me.”

The magic that’s truly missing from this “Camelot,” unfortunately, is the figurative kind that Mr. Sher has delivered so reliably in the past. The production doesn’t sing as much as it should — literally, in some cases, as a few other songs are, if not cut entirely, abbreviated. The aching “I Loved You Once in Silence” and the thundering “Guenevere” are sliced and sandwiched into a busy sequence, and “How to Handle A Woman” — one of the most moving love songs in the musical canon, in which Arthur reveals a tenderness that, tragically, he cannot express in his queen’s presence — is stripped of a short accompanying monologue and final chorus. 

My hunch is the monologue’s disappearance has something to do with a quaint joke in which Arthur mused about women not thinking too often. Mr. Sorkin’s Guenevere, played by a charming Phillipa Soo, is very conspicuously a thinker, prodding Arthur to conceive his vision of a just democracy and then helping him flesh it out, and effortlessly beating him at chess to boot. The king’s old acquaintance Morgan Le Fey (a wry Marilee Talkington) has been reimagined as even more of a brainiac, a scientist who can predict and articulate developments of the future century — while she’s pie-eyed on brandy, no less.

If this intellectual elevation of female characters seems self-conscious, a bigger problem is that the regal principals, Arthur in particular, seem at times to have been brought rather too far down to earth. One can certainly appreciate Messrs. Sorkin and Sher wanting to underline the king’s humanity, not to mention his relative youth, which has been lost in many interpretations. A Tony Award winner, Andrew Burnap is energetic and consistently appealing in the part, even when he and Ms. Soo are saddled with the especially obvious dialogue Mr. Sorkin provides to stress the English monarch’s inability to show affection for his passionate French bride.  

Yet the role of Arthur also requires a certain gravitas, which must carry over to the musical numbers. Burton couldn’t, despite his peerlessly robust speaking voice, match the technical singing prowess of his co-stars; but he was, as the original cast recording makes evident, a magnificent musical actor, and the best Arthurs have shared with him a vocal presence and instinct for phrasing that Mr. Burnap, however endearing, simply doesn’t demonstrate here.

It’s a relief, in fact, when Jordan Donica — by far the most powerful and charismatic singer of the three lead actors — takes the stage and delivers Lancelot’s opening number, “C’est Moi,” with an authority and vigor that is sustained throughout his performance, albeit duly tempered as the knight’s vulnerability becomes more apparent. There are other factors to recommend this production, from Taylor Trensch’s deliciously weaselly turn as Arthur’s scheming illegitimate son, Mordred, to Michael Yeargan’s elegant, majestic set design, which can indeed evoke a place where the rain may never fall till after sundown.

It’s a shame that this “Camelot,” despite its shining moments and impeccable pedigree, doesn’t offer more of that kind of splendor.