Talent and eccentricity have always had an uneasy relationship in the realm of music — they often travel hand in hand but don’t always get along. When stars do align, the outcome can be earth-shattering (see “Sgt. Pepper”), but all too often, it’s little more than a strange trip to the bottom of the oddity bin.

Fiona Apple, the Gen-X talent-eccentricity love child who’s lately become more famous for epic-length album titles than for making great music, has historically been able to delicately straddle this line. Yet on her third effort, “Extraordinary Machine,” Apple shows some major signs of strain: her repetitive songs amble without hitting a nerve, and her once-piercing lyrics have descended into stream-of-consciousness mush.

“Machine” was originally conceived as a collaboration between Apple and super-producer Jon Brion (Aimee Mann, Kanye West). Leaked to the Internet in early 2005, it became a bootleg hit for brooding B-girls the world over, only to be rejected by studio bigwigs. After some usual gossip-worthy studio wrangling, Apple tapped Eminem beat master Mike Elizondo for a fresh take on the bootleg material, trashing most of Brion’s work, save the first and last tracks. Thank God for that — the title song, one of Brion’s productions, is a messy hodgepodge of marimba and music hall-style clarinets.

From there, the album takes off on its second track. “Get Him Back,” with harshly resonant piano and drums, grooves and chugs like a well-oiled train. Elizondo has a masterful ear for rhythm, and on this song, the album’s crown jewel, he slides Apple’s trademark voice across a fantastically off-kilter piano loop and deftly-timed drums: it smacks of “Criminal” with a touch of Dave Matthews Band and a sprinkle of Tori Amos. The song’s energy and lyrical cohesion turn Apple’s hot, focused rage at the opposite sex into a giddy thrill ride. “One man, he disappoint me/ He give me the gouge and he take my glee/ Now every other man I see/ Remind me of the man who disappoint me,” she sings, warning male listeners not to mess with this hardened, scarred woman.”

Alas, “Get Him Back” is nothing more than a McGuffin — neither Apple nor Elizondo can sustain the magic. Musically, “Machine” quickly falls into repetition, and lyrically, it’s all over the map. Take these head-scratching lines from “Not About Love”: “Conversation, once colored by esteem/ Became dialogue/ As a diagram of a play for blood.” These non-sequiturs thin out what could have been a dense, probing lyrical exploration. It’s tragic, because 1996’s “Tidal” shows she’s capable of more, but on “Machine,” Apple displays a dismal lack of discipline.

The piano/drum combo that propelled “Get Him Back” to frenetic heights is resurrected ad nauseam on the rest of the disc, wearing thin by the eighth or ninth go-around. Even “O’ Sailor,” the third track, feels like it’s scrounging for some solid musical ground. The enervated piano loop strives for ominousness but instead hits boredom, while the dull drum line is a sad departure from the heart-pounding slaps of “Get Him Back.” Lyrically, it’s open season on Apple’s subconscious, to the utter confusion of the listener (“I have too been playing with fifty-two cards/ Just ’cause I play so far from my vest/ Whatever I’ve got, I’ve got no reason to guard/ What could I do, but spend my best”).

Even Brion’s sidelined oddball productions are preferable to the album’s tedious redundancy. In spite of this, Apple still keeps an ace or two up her sleeve — the hip-hop-flavored “Tymps (The Sick in the Head Song)” is a delicious diversion from the piano purgatory she seems stuck in. She’s at ease singing over the back-beat of bouncy drums and chirpy chimes, which Elizondo spices up the track with hand claps and some wonderfully campy synthesized organ. The song’s pensive mood and dance beat complement Apple’s playful lyrics, sweetly reminiscent of peak achievements like “Fast As You Can” on 1999’s acerbic “When the Pawn.”

Unfortunately, a rundown of the song list shows little in the vein of the creativity she displays on “Tymps.” On “Not About Love,” Apple and Elizondo attempt a blues-fusion workout, but it simply feels contrived, while the Radiohead-style beat on “Window” sounds awkward against Apple’s matter-of-fact delivery.

Justice is served, however, by the inclusion of “Waltz (Better Than Fine)” as the closing song. Brion’s only other contribution to the album, “Waltz” is an amusing, Beatles-esque orchestral number that revels in its own schmaltz — if the violins aren’t cheesy enough, the brass section pushes it totally over the edge. But in winking so slyly at its own outlandishness, the song accomplishes something that much of the album fails to do: it strikes the right balance between talent and eccentricity, between ability and experimentation, between genius and utter lunacy.