Its flagship program, “American Idol,” has been softening in the ratings for the past few years. It’s still the Death Star of television, but “Idol” is no longer getting the kind of ratings that cause executives at rival networks to spend their days under their desks, weeping over the latest Nielsen numbers.

But now Fox has “Glee” (8 p.m. Central Wednesday, WFLD-Ch. 32; three stars) which may not have an “Idol”-sized audience but is an unqualified hit, especially among the 18-34 demographics that advertisers (and television networks) prize. And “Glee,” which follows the progress of a rag-tag high school show choir, is a program that has learned the lessons of “Idol” well.

Though it’s a scripted show, “Glee” does what “Idol” does at its best: It creates moments of pure enjoyment. When a performer bristling with potential sings a good song really well, the result is exhilarating, uncomplicated pleasure.

Actually, “Glee” may go “Idol” one better: “Glee’s” singing-and-dancing production numbers are often fun and creative, unlike “Idol’s” clunky group sing-alongs, which are painful to watch. Someone on the “Idol” staff needs to pick the brains of “Glee’s” choreographers and directors.

Creating “Glee”-ful moments sounds simple, but it’s not. It takes exceptional performers, and in Lea Michele (who plays the pampered diva Rachel Berry), Chris Colfer (who plays the fantastically acerbic Kurt Hummel) and Matthew Morrison (who plays Will Schuester, the teacher who leads the club), “Glee” has three standouts. All three excel not just as singers but as actors, and even if the story lines they’re given are already getting repetitive, they make every scene they’re in worth watching.

Cory Monteith, who plays well-intentioned jock Finn Hudson, isn’t the most gifted singer in the cast, but he hold his own and his deft portrayal of Finn’s frequent befuddlement is a pleasure in itself. Other cast members have varying levels of talent and charisma, but the show’s go-to characters are so enjoyable — as was recent guest star Kristin Chenowith — that lesser performances fade a bit by comparison.

Still, the first volume of the “Glee” soundtrack, which came out last week, is a big hit in the Watcher household. Any TV show soundtrack that induces people of all ages to dance around the kitchen is doing something right.

Fun as it can be, “Glee” is not perfect, though Wednesday’s episode is a case study of what “Glee” does right. There are provocative and thoughtfully handled stories involving Artie (Kevin McHale), a character who is in a wheelchair, and Kurt, who has recently come out as gay to his father. Within the context of satire/dramedy with musical numbers, the show explores the question of difference — when differences should get special treatment and when they should not.

What Wednesday’s episode, “Wheels,” has that other episodes of “Glee” have lacked is coherence and narrative drive. Unlike “Idol,” which merely has to provide a couple of memorable performances and at least one zingy Simon Cowell quote, “Glee” is supposed to supply a story. Though the humor and music often take center stage, “Glee” is better when it has something to say, not just something to sing.

But some weeks, “Glee” has opted to haphazardly throw together a few intentionally soapy story lines (a teen pregnancy, the migraine-inducing Terri Schuester’s fake pregnancy, Will’s chemistry-free flirtation with a fussy fellow teacher, someone or other quitting the singing group for the millionth time) and hope for the best. The first season of the show is only one-third over, so it’s a bit troubling that some stories seem so tired and lazy already. And too often when a wobbly, slapdash episode threatens to fall apart — hey, how about a song?

Having said all that, I must acknowledge the show’s addictive elements. Dolton native Jane Lynch is giving one of the best performances on television as cheerleading coach Sue Sylvester, a driven woman who would be better suited to a gig as the dictator of small, fearful country. I must also note Iqbal Theba, who plays Principal Figgins with a perfectly calibrated mixture of world-weary ennui and canny opportunism. Any episode that has a lot of Sue, Figgins and Kurt and no Terri (Jessalyn Gilsig), as is the case with “Wheels,” is a win in my book. 

When “Glee” comes up with a well-proportioned mixture of drama and comedy and makes the arch, soapy stuff relatively painless (or better yet, gets creative with stereotypical soap storytelling), it’s one of the most enjoyable shows on TV. When it doesn’t, well, there are always Sue’s one-liners.

And if nothing else, there are those songs. Get out your hankies, because what these performers do with “Defying Gravity” on Wednesday will have you sniffling and smiling at the same time (“Glee’s” version of the song is here).