The first line is almost a perfectly regular line of iambic pentameter: "The silent banjo leans against the wall." It is calm and measured, like a still-life painting. Then the poem gets restless. The banjo becomes "a movie gangster, casual, coiled," and the hard c sounds tighten like a spring. A banjo has strings under tension, so "coiled" suits it, and the gangster simile makes the stillness feel dangerous. The banjo is waiting, "ready for some chin music." The phrase is slang for talk, and I believe it also comes from baseball, where it means a pitch thrown close to the batter's head. Either way, it promises music that might bruise.
The second stanza turns the threat into mystery. The banjo "may or may not / be in tune," and nobody knows which tuning it holds. The speaker's remark that "to some, this makes it alluring" is quietly funny, because it admits that we are drawn to what we cannot read. Then comes the oddest image in the poem: "Its neck is straight, like a mute swan / culled by a marksman." A living swan's neck curves in an S, so a straight one suggests a dead bird. The banjo's silence starts to look like a killing, and "culled" is a cold, administrative word for it. The pun on "mute" and "silent" ties the bird back to the instrument. The comparison also contradicts the gangster of the first stanza. The banjo is first the one who threatens and then the one who has been shot.
The two short stanzas that follow have the poem's most serious lines, set side by side in the same pattern: "The silent banjo is silent because." The repeated word "silent," seven times in all, almost wears itself out, until it sounds like a stubborn refusal. The first explanation is "it has seen too much," which makes the banjo a witness. The second is "no one remembers how to listen," which makes the audience the problem. The poem offers both reasons without choosing between them. The blame shifts from the object to us, and the reader is quietly put on trial. Neither line has any decoration. After the swan and the gangster, the plainness hits harder.
Then the tone changes again. "Approach the silent banjo as you would / any other apocryphon." An apocryphon is a text of doubtful authorship, often one kept out of the official canon, and the Greek root means "hidden." The banjo is now a forbidden book. The instructions turn mock-heroic: arrive "brandishing the one true book of matches." The pun on "book" is clever, because matches are what you use to burn the unorthodox books of the world. "The one true" borrows the language of religious certainty and makes it look silly. Then the final line, spoken in "your best Hollywood voice," is "The jig is up." A jig is a fast dance tune, the kind a banjo might play, and the phrase also means that the game is over. The line is a pun that gets caught up in its own joke, since it announces the end of the banjo's tune and the end of its disguise at once.
None of this is rhymed, and the poem does not need rhyme. Its glue is repetition: the opening phrase, the parallel stanzas, and the gradual shortening from four lines down to two before the long final stanza. The ampersands, in "& in what tuning" and "& saying," give the voice a casual, scribbled-down feel that suits the gangster-movie talk. That casualness is what lets the poem swerve so freely between swans, scripture and film.
The poem is worth reading because it is funny and uneasy at once. It never says what the banjo means, so the silence works as a test. The speaker's last move is to play the tough guy and burn the mystery away, but a joke made in a "Hollywood voice" is a nervous way to end. The poem suggests that when we meet something silent and strange, we tend to reach for a cliché, a pun or a match, rather than attempt the harder task named two stanzas earlier, which is to remember how to listen.