Learn Spanish (Latin America): Tal vez necesitas aflojar la tuerca con cuidado. - Maybe you need to loosen the nut carefully.

Phrases like tal vez and quizás can take either the indicative or the subjunctive depending on the speaker's level of certainty. Using the indicative (necesitas) means the speaker feels this is highly probable—maybe they are actively watching you struggle with a wrench. If they used the subjunctive (necesites), it would communicate a higher degree of doubt or guessing.

Is tuerca the same word I'd use for a nut that you eat?

No, tuerca refers exclusively to hardware—the metal nut that fastens onto a bolt (tornillo). If you want to talk about a nut you eat, you would use nuez (which specifically means walnut, but is often used broadly) or frutos secos for mixed nuts.

Could I use the adverb cuidadosamente instead of the phrase con cuidado?

You could, and it would be grammatically correct, but con cuidado is heavily preferred in spoken Spanish. Native speakers frequently use con + [noun] instead of adverbs ending in -mente because it sounds more natural and flows better in everyday conversation.

If I wanted to replace la tuerca with a pronoun to say "loosen it," where would the pronoun go?