A revival of the Fats Waller musical revue emphasizes the blues in its blueprints.PITTSFIELD, Mass. — I don’t know whether the creators of “Ain’t Misbehavin’” were sending a deliberate message of ambivalence by front-loading the 1978 revue, after its delightful title number, with a song called “Lookin’ Good but Feelin’ Bad.”In any case, the team behind the rousing Barrington Stage Company revival, playing through July 9 in this becalmed Berkshires city, sure are. The up-tempo zing of that song’s melody, by Thomas Waller, better known as Fats, never completely undoes the sting of a lyric, by Lester A. Santly, that speaks of “weary days and lonely nights” spent “grievin’ over you.”That’s because the double message in this “Fats Waller Musical Show,” as the subtitle puts it, is more than intentional: It’s emblematic. Leaving intact the original plotless structure — which Richard Maltby Jr. hammered together from 30 of the hundreds of songs Waller wrote or recorded — the director and choreographer Jeffrey L. Page has subtly shaped the show to push the “grievin’” further past romance and into the sphere of Black identity.That’s true even in the breezy first act, as five skilled performers sail through insanely catchy and often risqué songs like “’T Ain’t Nobody’s Biz-ness If I Do” (which Waller recorded) and “Honeysuckle Rose” (which he wrote with Andy Razaf). These numbers are set in Harlem between the world wars, specifically at the Savoy Ballroom, as Black artists perform for Black audiences.And though it’s hard to have deep thoughts while watching people jitterbug — or while listening to “The Joint Is Jumpin’,” the exuberant first act finale — you keep noticing phrases and attitudes that have been slightly retuned. If Maltby’s brilliant original production favored a perfect coat of Broadway gloss, the Barrington version, which he approved, looks for cracks in the show’s composure.Spangled, feathered and zooted: Jarvis B. Manning Jr., from left, Allison Blackwell, Anastacia McClesky, Maiesha McQueen and Arnold Harper II in Oana Botez’s playful costumes.Daniel RaderSometimes, it’s a matter of design. Oana Botez’s exaggerated costumes — the three women profusely spangled and feathered and the two men wearing the zootiest zoot suits ever — suggest that even the playfulness of self-advertisement amounts to a form of disguise. Hidden in the proscenium of Raul Abrego’s black-and-gold Art Deco set are images of African masks.But in the second act, the meaning of the masking changes, as the uptown artists grow more popular among the downtown, mostly white crowds cartooned in “Lounging at the Waldorf.” (“They like jazz but in small doses,” goes a Maltby lyric for a Waller instrumental. “Bop and you could cause thrombosis.”) Soon the trade-off of authenticity for popularity becomes more disfiguring, as songs like “Your Feet’s Too Big,” “Find Out What They Like,” “The Viper’s Drag” and the devastating “Mean to Me” offer a performative version of Blackness that exaggerates stereotypes of belligerence, concupiscence, addiction and abandonment.Eventually, after an egregious bit of minstrelsy called “Fat and Greasy,” when the high spirits become impossible to maintain, the show takes a silent, sour pause. This puts “Black and Blue,” the climactic number, in a new context, or perhaps a clearer version of the original one. Its lover’s complaint of a lyric — “Browns and yellers, all have fellers/Gentlemen prefer them light” — moves outward to a consideration of injustice, in which the value of Black skin (“my only sin”) is set by white beholders.You wouldn’t think a show that trades in virtuosic swing could drop so deep and keep its balance, but then an ambivalence about appropriation is clearly part of Waller’s blueprint. (The tricky piano runs aren’t running from nothing.) Yet Page never goes so far as to strip the songs of their ticklish pleasures while stripping them of their varnish. More varnish might actually help; opening after just three days of previews, the production needs more shine. The sound is still muddy and the lighting still awkward. The performers, at first, are a bit of both, acting the lyrics too insistently, with a gesture for every word.Soon, though, they settle down, each delivering a specialty number that recalls (and then lets you put aside) the stellar original cast. Maiesha McQueen, singing Nell Carter’s songs, delivers a heartbreaking “Mean to Me”; Jarvis B. Manning Jr., taking on André De Shields’s track, is especially compelling in “The Viper’s Drag,” a song about smoking weed in which his body seems to become smoke itself. The others — Allison Blackwell, Arnold Harper II and Anastacia McClesky — all have great moments; the seven-person band, led by Kwinton Gray, has nothing but.Back in 1978, “Ain’t Misbehavin’” celebrated songs and performers from an era — the 1920s and ’30s — within many people’s living memory. Now, more than 40 years later, it’s important to replenish the context that time has drained. Even a show so universally admired benefits from thoughtful reconsideration. I don’t mean updating but something more like what happens in this production when we hear Luther Henderson’s stunning arrangement of “Black and Blue,” largely unchanged. It’s then that a deco drop flies up to reveal the back wall of the theater, as if what Waller swung and sang the blues about were happening now. It is.Ain’t Misbehavin’: The Fats Waller Musical ShowThrough July 9 at the Boyd-Quinson Stage, Pittsfield, Mass.; barringtonstageco.org. Running time: 2 hours. More