When the folks at Chanhassen Dinner Theatres decided to create a substantive stage work out of the 1948 movie "Easter Parade," their main challenge was to create a stage presentation out of a winsome but witless piffle made for the likes of Fred Astaire and Judy Garland.

As of opening night, they've done about three-quarters of the job. Painstakingly and lovingly rendered, "Easter Parade" is no longer a mere star vehicle, but neither has it completed its evolution.

Is it a turn-of-the-century backstage musical? A collection of specialty numbers and spectaculars by the inimitable Irving Berlin? A narrative-driven tale of star-crossed lovers and their egos?

Ultimately, book writer Tom Briggs and director Michael Brindisi seem to want their stage creation of "Easter Parade" to be all of those things. They've re-jiggered the story and its mood just enough to create some depth in the characters, and things end with a romantic twist different from the film.

There's no shortage of fabulously costumed, intricately choreographed, genuinely imaginative production numbers. Choreographer Tamara Kangas and costumer Sandra Nei Schulte should get bonus pay for the raucous "When the Midnight Choo-Choo Leaves for Alabam' " and the tropical "Shakin' the Blues Away."

The show's quiet moments are effective. "Mr. Monotony," a duet sung by leading ladies Michele Barber and Ann Michels, is clarion, honest and thematically propulsive; hands down the best scene of the show.

And like any good, old-fashioned musical comedy, this one has a couple of memorable tertiary characters — Angela Timberman and Jay Albright as a mouthy backstage maid and her still-waters-run-deep boyfriend — and gives the audience a chance to cheer for them after the chipper and cheeky ditty, "You'd Be Surprised."

Still, it doesn't all quite flow. Running a not unreasonable 2½ hours with intermission, the show feels long because the storytelling lacks velocity. A hackneyed framing device using a newsboy — the not especially well-cast Samuel Patrick Faunillan — hurts more than it helps. In the second act, the narrative grinds to halt for the sake of back-to-back production numbers.

That might be all right if Briggs and Brindisi were willing either to commit to the story or let it slide.

Instead, they steer an odd middle course, with self-centered hoofer Don Hughes (Astaire in the movie, here the solid if slightly slick Michael Gruber) undergoing an unexplained change of heart just in time for the finale, and the unobtrusive, moony press agent (Keith Rice, in typically fine voice but wearing emotion too plainly on his sleeve) getting a girl at the end.

Those who would shut up about dramaturgical fineries and just enjoy the spectacle would have a better time at "Easter Parade," but they'd be missing the larger point. Chanhassen, with a reputation for breathing inspired new life into old musicals, is attempting to make a new contribution to the musical theater canon with "Easter Parade." It's a noble effort, and one worth pursuing. But it's not done yet.