There’s no denying the utter delight in seeing Alex Winter and Keanu Reeves back in the guises that made them famous, time-traveling slacker-rockers Bill and Ted.

Winter’s broad, goofy grin, Reeves’ trademark befuddlement — you don’t realize you’ve missed them until you see them again, older, still-in-character, still clinging to the Wyld Stallions dream.

Maybe thirty-one years later they have one more “excellent adventure” in them. Maybe we all do. Maybe not.

Sure, they say “twenty-five years” in the movie. But who doesn’t lie about his age, right?

Decades of pleading fanboy film journalist questions later, they finally made a third movie, a sentimental and cheerful affair that doesn’t amount to much more than an attempt to tap into their residual good vibes. And the glee that they sell their little air guitar moments with in “Bill & Ted Face the Music” makes you root for them, even as the jokes are strained, the moments of wit thin and the pacing not nearly as manic as a zippy zig-zag through time — by themselves and those closest to them — ought to be.

The original screenwriters return, and comedy veteran Dean Parisot (“Red 2,” “Galaxy Quest”) steps behind the camera. The guy knows comic action nostalgia. Or should.

But this too-little, almost-too-late sequel never grabs hold of giddy and never amounts to much at all, just a belated attempt to recapture lightning in a bottle.

Our two dudes are old marrieds now. But their constant togetherness — even taking couples therapy as two pairs– have driven their Medieval wives (Erinn Hayes and Jayma Mays, replacing the “Bogus Journey” Medieval wives) to distraction.

They’ve raised two music-addicted slacker daughters, Thea (Samara Weaving) and Billie (Brigette Lundy-Paine).

And the Wyld Stallions are still doggedly making music, trying to come up with that one song “that will bring the world together.” But introducing “That Which Binds Us Through Time…the first three movements” isn’t likely to convert anybody to Tibetan chant mixed with a Therimin, bagpipes, etc.

While it may not matter to Rufus (the late George Carlin), his widow (Holland Taylor) now has The Great Leader gig. And she sends her daughter (Kristen Schaal) to fetch the dudes, chew them out and give them 77 minutes to get the song done before space and time tangle up end.

“Whoa.”

Events conspire to send Bill & Ted hurtling through time, via that time traveling phone booth, visiting their later selves, trying to find that point in the future when “we’ve already WRITTEN” the song.

Their daughters talk time-traveling Kelly (Schaal) out of her traveling egg and set out to build their dads the perfect backup band — Jimi Hendrix, caught mid-rehearsal, Louis Armstrong before he became a superstar.

“So what you’re all saying is that you love a song that I write in MY future,” Louis (Jeremiah Craft, good) ponders…

“Which is in YOUR past,” adds Jimi (DazMann Still)…

“But we’re in THIS present (1782 Vienna, recruiting Mozart).”

This “getting the band together” bit is rushed through — ancient Africa for a drummer, ancient China to grab famous composer-flutist Ling Lun, seen as a woman here (Sharon Gee). But too little of the film has that pacing.

The actresses playing the daughters are cute and take their shot at getting that Bill & Ted offspring quirk about them. It must skip a generation. The script isn’t a great help to them, but neither young lady is the least bit funny.

So you reach for the simple pleasures, the way our dudes’ eyes light up when taking up the air guitar again, their return to Hell to visit the droll German-accented Death (William Sadler), whose career as a solo bassist never took off and thus isn’t happy to see them.

“TALK to der hand!”

The many incarnations of Bill & Ted that the lads visit earn just a grin here and there — Bill & Ted in prison, comically muscle-bound, balding in a nursing home, etc.

Actor-musician Kid Cudi turns up as himself, the “Doc Brown” of this version of the tale, explaining the science and time travel paradoxes they’re up against as they scramble to “save everyone.”

It can’t have been easy engineering a story that would bring them back, please the stars, “play as young” as the originals and come off as fresh and funny. The “Bill & Ted” films are more beloved than hilarious, charmingly shambolicl. It’s always been about the characters.

One line from the script should have been an edict to the screenwriters, a line Bill and Ted repeat to each other with each time trip to try and fix the present via the future.

“Make it better, not worse!”

Alas, as sweet as some of this is, they rarely do.

Cast: Keanu Reeves Alex Winter, Kristen Schaal, Samara Weaving, Brigette Lundy-Paine, Jayma Mays, Erinn Hayes, Kid Cudi, Holland Taylor and William Sadler

Credits: Directed by Dean Parisot, script by Chris Matheson and Ed Solomon. An Orion/MGM release.

Running time: 1:31