The line is a unit of attention, not a unit of grammar
A prose sentence is a unit of grammar. A free verse line is a unit of attention: it says look at this much, then stop, then look at the next thing. When you read the specimen aloud and pause at every line break, lines 5 to 7 become three separate looks at a two-word instruction. That is the effect of the break, not of the words.
If a draft reads exactly the same when you re-flow it as prose, the breaks are doing nothing. That is the first test, and it is free.
Three kinds of break, and when to use each
A hard break ends a clause and the sentence stops with it: line 13, does not mind. A soft break cuts mid-phrase so the syntax runs on: line 1 to 2, the lid / of the pump. A stressed break puts the important word alone on the line: prime, and, before, at lines 5 to 7.
A workable rhythm in English free verse is roughly two soft breaks to one hard break, with a stressed break used once or twice in a poem of twenty lines. Use a stressed break more often and it stops being an accent and becomes a tic.
The revision method: re-break it three ways
Type the draft once as a paragraph. Then break it again from scratch three times, aiming for a different line length each time — a short-line version of four or five words, a medium version of six to eight, and a long version that runs to the page margin. Read all four out loud.
The version that survives is rarely the one you wrote first. This works because line length is the single biggest control you have over pace, and pace is what free verse is actually made of. Two related dials: end the line on a stressed syllable to slow down, on a preposition or article to hurry the reader into the next line.
What not to do
Do not break the line where you would take a breath. Breath breaks produce lines of roughly equal length with no argument behind them — the reader hears a metronome. Break where the meaning changes direction, not where your lungs change direction.
Do not use a short line to make a weak line look important. A three-word line reads as emphasis, so if the words are not emphatic, the emphasis lands on nothing and the poem loses credit for the next one.