To make the point in terms fans of the first movie will understand, it would take more than a few sprays of Windex to fix Nia Vardalos’ script for “My Big Fat Greek Wedding 2,” a sequel that’s taken almost as long to reach the screen as “Zoolander 2,” and is only marginally better than that catastrophe. Members of the colorful Portokalos clan rarely leave their Chicago home, it appears; but the lesson of “Wedding 2”—and of the failed CBS spin-off sitcom “My Big Fat Greek Life” that lasted only seven episodes in 2003—is that while Vardalos can go home again, she shouldn’t have bothered, and certainly viewers would be well advised to skip this return trip.

The plot finds Toula (Vardalos) and hubby Ian (John Corbett), as well as many of her relatives, living in a series of suburban houses along a single street, all situated just down from that of her parents, crotchety Gus (Michael Constantine) and outgoing Maria (Lainie Kazan). She works at the family’s restaurant Dancing Zorba, and he’s the principal of the neighborhood high school where their daughter Paris (Elena Kampouris) is a senior, looking to enroll at a college far away from her clinging parents and suffocating clan—Gus in particular insists that she meet a Greek boy and get married before she’s “too old.”

It’s not Paris, however, who will wed by the time the new movie is over. In doing Internet research to prove that he’s a direct descendant of Alexander the Great (it’s the old fellow’s introduction to a computer—har, har!), Gus comes upon his marriage certificate from the old country, which he finds was not properly signed by the officiating priest. That means—horrors!—that he and Maria aren’t really married. And when his perhaps-wife learns the news, she decides to put off taking the vows again until Gus does her the honor of proposing properly, something the stubborn old goat refuses to do until a slapstick incident involving a bathtub induces him to profess his love once more. The balance of the picture involves everyone in the family chipping in to make their big, fat wedding a reality.

This premise of the marriage that wasn’t is certainly one of the hoariest in the Hollywood script playbook. It’s been used in scads of pictures, including Hitchcock’s “Mr. & Mrs. Smith” in 1941. Resuscitating it here seems more an act of desperation than of inspiration. But Vardalos compounds the archaic feel by juxtaposing it with the effort of Toula and Ian to breathe new life into their own marriage, which has gone somewhat stale in the intervening years as work and parenting have taken their toll. That leads to some slapsticky efforts to reinsert spontaneity into their love life even as they’re absorbed in Gus and Maria’s situation. Frankly Vardalos and Corbett’s commitment to this portion of the tale comes across as halfhearted at best. And a further subplot about Paris’ college choice and her infatuation with cute classmate Bennett (Alex Wolff) doesn’t bring many rewards, either; a college-day sequence in the HS gym (featuring Rob Riggle as a recruiter from Northwestern) falls especially flat.

Still, fans of the first movie may be amused by Constantine’s antics, which are center-stage this time around, and by the take-charge attitude of Andrea Martin’s Aunt Voula, who revs things up with her willingness to say anything whenever the movie’s rhythm feels as though it’s going slack, which is pretty often. The down moments also invite cutaways to the dour figure of the family matriarch (Bess Meisler), whose mute reactions are always good for an easy laugh. But apart from a few moments of volubility, Kazan proves only fair, and little levity is provided by Louis Mandylor as Toula’s brother or by Gia Carides and Joey Fatone as her cousins. (A big revelation about the latter’s love life—and the family’s reaction to it—comes across as a patronizing attempt to drag what’s really a fifties-style ethnic sitcom into the modern world.) Even flatter are a sub-subplot involving a new couple to the neighborhood, played by John Stamos and Rita Wilson, the introduction of Gus’ stay-at-home brother (Mark Margolis)—whose toast to the drachma might cause some cringes, given Greece’s current economic crisis—and a trio of local harpies whose rude comments about the Portokalos clan act as the occasion for a supposedly heartfelt outburst by Toula that feels utterly artificial.

Directorial duties for “My Big Fat Greek Wedding 2” have been turned over from Joel Zwick to Kirk Jones, who continues to prove that the charming quirkiness of “Waking Ned Devine” was a fluke; his work in this instance can barely be called adequate. The technical credits, from Jim Denault’s cinematography on down, are okay across the board, though not much more than what one would expect of a cable movie. Anybody looking for signs of the Chicago locale will be disappointed; this is another Toronto shoot.

Nostalgically-minded older views might find this a harmless way to spend a Sunday afternoon. But most will find it one wedding too many.