“Getting the band back together” nostalgia is fine. Realizing that they can still play well into their ’70s is something of a “good for them” triumph.

And maybe coming to the conclusion that for a parody of a bombastic, pretentious British heavy metal band of the ’60s through the ’80s, tunes like “Big Bottom,” “Hell Hole,” “Flower People” and “Stonehenge” pretty much hold up.

But as amusing as it’s been over the years for “the lads” of Spinal Tap to turn up on late night chat-variety shows to prove they’re as musical and as clueless as ever, a sequel to “This is Spinal Tap,” the mockumentary that really invented that label, can’t help but play as winded, gassed, joked-out and pointless.

“Spinal Tap II: The End Continues” comes off like what used to be called “a contractual obligation album,” or a chance to re-record and grab the rights back to their music and the movie that made them. They might finally profit from a fake band, their fake band back catalog of tunes and that fake documentary that Nigel Tufnel, Derek Smalls, David St. Hubbins and director Marty DiBergi barely made a dime from.

That goes for their creators, Christopher Guest, Harry Shearer, Michael McKean and Rob Reiner as well. It’s ironically hilarious that the guys who made the movie about the clueless fake band were clueless enough to sign the worst deal possible with distributors, just to get the original film made.

But the bottom line is, that’s why “Spinal Tap II: Finally Cashing In” exists.

Guest’s mockumentary career went its course, and he tried a filmmaking comeback with Netflix (“Mascots”) that didn’t work out a few years back. McKean has worked steadily in supporting roles (“Better Call Saul,” “The Diplomat”) and voice-over work in the intervening years — nothing to make one rich. And Reiner’s acted a bit, even as his directing career fell off dramatically after the charming “Flipped” flopped fifteen years ago.

Shearer? He’s had his lucrative “Simpsons” gig since the ’80s. He’s fine. Which is perhaps the reason he’s not credited as a writer here, and that he has little to say or contribute that’s funny. He’s just the bass player, man. He just has to show up.

Derek’s running The New Museum of Glue these days. Nigel runs a Cheese & Guitars Shop. St. Hubbins is making music for podcasts.

Reasons more contrived than logical broke them up, and now they’re reuniting for a big New Orleans comeback/farewell concert. They audition or approach famous drummers (Lars Uhlrich, Questlove, Chad Smith) and little knowns (including a Blue Man Group alumnus) to replace the “eleven” they’ve killed off.

Riot Grrrrl Didi (Valerie Franco) gets the gig. They add Caucasian Jeff (CJ Vanston) on keyboards, cope with a new manager, Simon (Chris Addison) and the fangirlish daughter (Kerry Goldiman) of their original manager and settle into the rehearsal studio where the parade of famous cameos continue, none of them to hilarious effect.

Trisha Yearwood and Garth Brooks to Paul McCartney and Elton John join the deadpan parade, and some manage to drag out a smile or two as they’re insulted, or turn insulting.

But in the 41 years since Spinal Tap sent-up the supposedly then-just-passed “classic rock” era, communities from coast to coast have opened outdoor concert venues that only yacht rock and classic rock and other nostalgia acts can fill. Promoters call these ampitheatres “Jurassic Parks.”

“Classic rock” hung around. Bad Company just got into the Rock Hall of Fame.

Comical documentaries about real bands of the genre that never quite made it (“Anvil!”) have come out. And Guest made a whole career out of mockumentaries, even tapping into old folk musician nostalgia (“A Mighty Wind”) for one film.

Clips and outtakes from the original film take us back. But the music they sent up never went away, even if they did. For a while.

The joke is played, the conceit is worn out and seeing granddad-bod Guest in a kilt isn’t nearly the hoot one might have hoped.

So if you want to support this crew getting control of their amusing and enduring intellectual property, I’d suggest you give the documentary a pass and just buy the concert LP. “Hell Hole” still rocks, “Big Bottom” still rolls, and you know “Stonehenge” will finish with a crash, with or without dwarf druids dancing in the ruins.

Rating: R, profanity

Cast: Michael McKean, Christopher Guest, Harry Shearer, Rob Reiner, Valerie Franco, CJ Vantston, Kerry Godliman, Chris Addison, with Trisha Yearwood, Lars Ulhrich, Garth Brooks, Paul McCartney and Elton John.

Credits: Directed by Rob Reiner, scripted by Christopher Guest, Michael McKean and Rob Reiner. A Bleecker Street release.

Running time: 1:23