Throughout the majority of The Beatles: Get Back, the extensive documentary chronicling the one-month deadline that The Beatles put on themselves to complete an album, a live performance, and a TV special, John Lennon keeps circling back around to one song.

While ‘Dig a Pony’ gets thrown into the mix when Lennon can’t quite think of anything better to do, the main piece that he struggles to work through is ‘Don’t Let Me Down’. He arrives with the song during the band’s first few days of rehearsal at Twickenham studio— or at least he arrives with the chorus: the rest of the song is unfinished, and Lennon continuously makes up or modifies what he wants throughout the song’s gestation period.

Lennon clearly doesn’t know what he wants for the song, and so he plunders his old material for inspiration. ‘Across the Universe’, a charity single recorded a year prior, is dutifully taken back out, as is a Lennon/McCartney tune from their earliest days of collaboration. Lennon also jams out a nonsense song called ‘Dig It’ before he ever has a final version of ‘Don’t Let Me Down’ in the bag.

Back at Twickenham, Paul McCartney begins to dictate to the other band members what he thinks they should play. He instructs George Harrison to sustain his notes throughout the verses, and tells Ringo Starr to play sixteenth notes on the cymbals to add colour. McCartney also attempts to add a call and response section during the “I’m in love for the first time” verse, but that eventually gets scrapped from the final take.

Even when the band seemingly have it ready to run as they ascend to the top of the Apple studio roof, Lennon still flubs the lyrics to one of the two versions they play. It’s a microcosm of his mindset at the time: unfocused, somewhat aimless, but occasionally brilliant. The saddest part is that all of Lennon’s hard work was for nothing: Phil Spector wound up cutting ‘Don’t Let Me Down’ from the final tracklisting of Let It Be, and the song only served as the B-side to the ‘Get Back’ single.

The footage is remarkable for the small bits that would have gotten lost taking the bigger picture into account: the obtrusive presence of Harrison’s friends from the Hare Krishna movement, Lennon’s brief mention of Arthur Alexander (whose song ‘Anna’ was covered by the band on their first LP Please Please Me), and other elements that serve to clear up what it was actually like to chip away at the project.