"Mary Poppins Returns" works hard to evoke the undeniable charms of the original 1964 film: It replicates many of them, in slavish fashion.

Remember that famous animated set piece from the first film in which live-action characters jump into a two-dimensional sidewalk chalk drawing? Here, they leap into a painting on a ceramic bowl. And how about that "Step in Time" number from the original, featuring dancing chimney sweeps? In the sequel, it's a phalanx of London lamplighters performing parkour tricks on bicycles.

Half a century ago, Ed Wynn, as Mary's eccentric uncle Albert, floated up to the ceiling as if filled with helium while singing "I Love to Laugh." Now it's Meryl Streep's turn, as Mary's eccentric cousin Topsy, trilling "Turning Turtle" as she gives a tour of her upside-down repair shop.

I mean, homage is one thing, but this reeks less of nostalgia than sweat. There is so little tolerance for spontaneity, in a film that feels calibrated to the millimeter to be magical, that reactions like delight and surprise - when they occur at all - feel manufactured.

Set some 20 years after the action of "Mary Poppins," "Mary Poppins Returns" centers on the now-grown Banks children: Michael (Ben Whishaw), a widower with three children (Pixie Davies, Joel Dawson and Nathanael Saleh), and his unmarried sister, Jane (Emily Mortimer). Jane, like her suffragist mother before her, is an activist for progressive causes (in this case, SPRUCE, or the Society for the Protection of the Rights of the Underpaid Citizens of England). Her soft heart for the working stiff - coupled with her status as a singleton - makes her a perfect candidate for the love of Lin-Manuel Miranda's Jack, a lamplighter who we're told was once an apprentice of Dick Van Dyke's character, Bert, from the 1964 film.

(Sadly, although Miranda is a deft and effortless dancer, with a genial singing voice, there is little, if any, chemistry between him and Jane. And while affable enough, the creator and star of "Hamilton" has little screen presence. Don't even get me started on his cockney accent, a vocal misfire that makes Van Dyke's mangled vowels sound good.)

Michael, a scatterbrained artist, is distraught because he misses his late wife. In fact, his grief has prevented him from keeping up with the mortgage payments on the house, which has fallen into foreclosure as the film opens, under the predations of a heartless banker played by Colin Firth. Strangely, Michael's heavy mood of gloom and doom pervades this family tale, like the "misty morning showers" that Miranda sings about, euphemistically, in the movie's pleasant if underwhelming opening number, "(Underneath the) Lovely London Sky." The songs by Marc Shaiman and Scott Wittman are serviceable, if less memorable, than the original songbook by the Sherman brothers, Robert and Richard, who wrote such unforgettable earworms as "Supercalifragilisticexpialidocious" and "Let's Go Fly a Kite."

Into this musical miasma of fog and funk floats the title character (the excellent Emily Blunt, pitch-perfect as the punctilious-to-the-point-of-snarky Poppins) to set things right. Two hours later, after exhausting digressions, surreal side trips and interminable interludes that make the first film, at nearly 2 1/2 hours, somehow feel shorter than this one, Mary's mission is accomplished. (Have I mentioned that this is a Disney film? A happy ending - including a surprise cameo that is as close to enchanting as the movie ever gets - is never really in doubt.)

Surely there are some who will approach the naked mechanics of "Mary Poppins Returns" more generously than others. Fond memories of the first film, and a childlike acceptance of the movie's almost desperate need to be liked, can go a long way toward sweetening what left a bad taste in my mouth: its shameless sense of imitation and the all but joyless drumbeat of duty. Where's the spoonful of sugar, you may wonder, to help this medicine go down?

'Mary Poppins Returns'

One and one-half stars out of four. Rated PG. Contains mildly mature thematic elements and brief action. 130 minutes.