Touches within individual performances, a clever unraveling of a table cloth, a few strong scenes, including the most crucial to the musical, and the lasting quality of Stephen Sondheim’s lush, witty score and Hugh Wheeler’s well-crafted book keep the Princeton Festival production of “A Little Night Music” from succumbing to missing elements that threaten to scuttle it.

Those missing elements are elegance and sophistication. There’s an ordinariness and lack of polish to the characters in Diana Basmajian’s staging. Wheeler’s lines don’t always play crisply, so jokes and bons mots are lost and, on occasion, seem misunderstood or unnoticed.

Running past a joke is preferable to pushing it or overemphasizing it, but the Princeton Festival cast, with the exceptions of Camella Clark (the Countess) and Anastasia Zeiler (Fredrika), didn’t seem to appreciate the humor at all. They played their scenes as if they were in drawing room comedy rather than a smart, stylish musical about the romantic foibles of people with alleged taste and refinement. The approach to lines and characterizations seemed more operatic than theatrical.

“A Little Night Music” can benefit from simplicity, as Basmajian’s production sometimes proves, but many line readings in Princeton covered only the bare minimum and left a lot of texture and depth behind. Sondheim and Wheeler’s redolent gloss was too often glossed over.

Luckily, weak acting often gives way to strong singing. Musically, and primarily vocally, this “A Little Night Music” improves remarkably when characters are singing. Some nuance in Sondheim’s lyrics is missed, but the voices sound lovely.

Jesse Malgieri (Count Malcolm) finds true power and sensitivity to material when he launches into the Count’s clever songs. Jami Leonard’s operetta-ish Anne takes on some luster when her beautiful, effortless soprano is heard. The chorus, which serves as commentators, onlookers, and an extra character here and there, is uniformly excellent. Michael Kuhn’s magnificent and distinct tenor voice is especially welcome in solo lines.

The lack of sophistication is grating in the opening scenes of this “A Little Night Music,” especially those in the Egerman home. But the disappointment at the reduced tone of Wheeler’s book subsides as Basmajian’s production proceeds, and you get more accustomed to how the characters are being played.

It’s then that you notice that Wayne Hu (Fredrik) brings some clever irony to his performance that shows Fredrik is aware he’s been an old fool in some of his choices, including marrying the 18-year-old Anne, who remains a virgin after 11 months as a wife. You also begin to appreciate more of Jessica Medoff’s approach to Desiree, the woman of the world who has known many a man and seen many a bed.

At first, Medoff’s take seems too brusque, too much the Broadway dame who has experienced so much, she scoffs at everything and goes through life like a steamroller pulverizing all in its wake, “Gypsy’s” Mama Rose without the charm. Medoff doesn’t endow Desiree with much of the intelligence and class with which the character softens her worldliness. Yet she acquires a womanly warmth and eventually earns our interest.

Just when you think Medoff’s Desiree is too common for the musical’s good, she fools you by revealing some of the character’s wisdom. The single best scene in Basmajian’s production is the most important, the one in which Desiree embraces her folly at trying to snare her bygone lover, Fredrik — now married to an ingenue — into renewed romance, and perhaps more, during a well-plotted but disastrously thwarted weekend at her mother’s country estate. Medoff suddenly shows you a woman with her blinders off and her scheming over.

Magically, when she sheds Desiree’s illusions, Medoff also lets her acting guard down, and her scene with Hu’s Fredrik is sincere and suffused with all of the depth and elegance that has been missing to that point. Sincerity, in conversation and attitude, take over. You’re seeing something real instead of something performed.

Hu takes a cue from Medoff and is also more direct and natural than in previous scenes. In addition to making one of musical theater’s best scenes work gloriously, Medoff’s surrender to Desiree’s reality also sets up Sondheim’s best known song, “Send in the Clowns,” and gives it perceptive, heartbreaking depth.

Given what comes before, all of this is a surprise, but what a pleasant, exhilarating one. The bedroom scene with Desiree and Fredrik sets up the remaining 15 minutes of the production, and Basmajian’s staging actually ends poignantly and with the irony of an early scene when Desiree’s mother (Brook Packard) describes the smiles of the summer night, as delineated by Swedish filmmaker Ingmar Bergman in the 1955 film on which “A Little Night Music” is based.

Other fine moments in Basmajian’s staging include Lara Treacy’s singing of “The Miller’s Son”; Camella Clark’s arch readings and self-deprecation, especially when she catches herself doing her husband’s nefarious bidding; the brilliant way in which a table cloth is spread for the dinner scene; the equally creative use of traveling trunks as automobiles; and any moment that includes the production’s youngest cast member, Anastasia Zeiler.

From the opening moment, in which Zeiler begins a dance that expands to the entire cast, this young actress shows spirit, vitality, and kinship with the Sondheim-Wheeler material that eludes her elders. Zeiler always brings freshness to the Princeton stage and plays Fredrika’s precocity, and tutelage by Desiree’s fellow actors, well.

James Cochran was on target as the outraged divinity student, Henrik Egerman. Karina Sweeney and Matthew Kolb provide some wry vocal turns. Lance Channing is fun as the butler, Frid. And in the long run, Basmajian moves all efficiently and succeeds in providing a pleasant entertainment.

A Little Night Music, Princeton Festival, 185 Nassau Street, Princeton. Through Sunday, June 26, Thursday through Saturday at 8 p.m. and Sunday, 4 p.m. $35 to $45.

Other Princeton Festival events:

Peter Grimes, Saturday, June 18, Thursday, June 23, Sunday, June 26, McCarter Theater. $30 to $140.

Organ Concert by Kristiaan Seynhave, Sunday, June 19, Princeton University Chapel. $10 to $35.

Jazz vocalist Cecile McLorin Salvant, Sunday, June 19, McCarter Theater, $45 to $60.

Princeton Festival Baroque Orchestra, Wednesday, June 22, Miller Chapel, Princeton Theological Seminary, $25. 609-258-2787 or