The best reason to see “Trainspotting,” Harry Gibson’s Irvine Welsh adaptation now running at the Elephant Stages, is lead actor Justin Zachary, who invests junkie protagonist Mark Renton with understatement, wit and even grace – even more so than did Ewan McGregor in Danny Boyle’s 1996 movie version.

Actors love to take on hapless gobshite parts, in which they take center stage and get to go through so many flashy emotional hoops. But as most such losers swirl around and around the toilet bowl without making any effort to pull themselves out, they can be deadly boring to watch. Zachary is smart and skilled enough to let us in on Mark’s ambivalence toward his sloppy, downhill lifestyle. He gets us to root for him and care about him even at the character’s most self-indulgent. That’s a rare gift.

Zachary aside, this production is a misfire in three significant ways, starting with the set. If you want to create a phantasmagoria of the Edinburgh lower depths – and script, staging and lighting do suggest that’s the intent – then a raised platform with heavy wooden chairs and working door, with a long wooden box (suitable for bed, bench or coffin) on floor level, is going to work against the evening’s taking off. Getting rid of all the masking and realistic detail would’ve gone a long way toward creating a fluid environment suitable to the text. (Would’ve omitted 20 minutes’ worth of clunky entrances and exits, too, a boon to a production now wildly overlong at 2:35.)

Then there are the accents, which sound Scottish enough but don’t give enough of a nod to English. In other words, the diction is atrocious. (One character, a Vinnie Jones football hooligan type, keeps roaring in with lengthy rants, during which actor Matt Tully never manages a single intelligible sentence.)

Forcing an audience to try to make out garbled exposition and laugh lines on the fly for the better part of three hours is the height of vanity.

But the biggest problem is with Gibson’s dramaturgy, which largely involves first person, present tense narration on the part of Mark, meaning we’re constantly being told exactly what he (and we) are seeing: “She retches.” “I hear her scream.” Whether these lines are spoken before, during, or after the retching or screaming, all that’s created is redundancy.

Here’s Mark on pal Sick Boy (Jonathan Roumie): “His face looks ugly – leering, reptilian.” A book-on-tape would offer a nice image for the listener to chew on; a film could present the ugly face in closeup or with fisheye distortion and add something to the moment. But on stage, Roumie either lives up to the description or he doesn’t, and either way you ask yourself, “Why do we keep hearing about the exact same things we’re witnessing?”

This production is evidently a revival of a production of some 11 years ago, featuring Zachary, director Roger Mathey, and several other thesps. I didn’t see it, but am told it was widely acclaimed, perhaps because of the undeniable gusto with which Welsh’s famous grossout setpieces are performed. The dead baby, Mark’s waking up covered in his own feces, the hunt for the suppositories in a filthy bog – that’s all executed with an admirable lack of self-consciousness. It’s all the fookin shite in between I object to.

“Trainspotting” is scheduled to run through May.