Learn Farsi: پمپی که آن را تعمیر کردید، دوباره خراب شد.

In Farsi, when a relative clause describes a direct object, we usually repeat the object inside the clause using a pronoun. This is called a resumptive pronoun. So literally, Farsi says "The pump that you repaired it, broke again." Here, ân means "it" and râ marks it as the direct object of the verb "repaired".

Could we use an attached pronoun instead of ân râ here?

Yes! Instead of using the separate words ân râ, you could attach the object pronoun -ash (it) to the verb. The phrase would become ke ta'mir-ash kardid. Both mean the same thing, though using ân râ is very common and can sound slightly more explicit.

If we are talking about a specific pump ("The pump"), why does pomp have the -i suffix (pompi) which usually means "a" or "an"?

When a noun is followed by a ke (that/which) clause, it usually takes this special -i suffix. It is called the relative -i and acts as a bridge connecting the noun to its description. Even though it looks identical to the indefinite suffix for "a", here it singles out exactly which pump we are talking about.

Why do we use shod (became) in kharâb shod to mean "broke"?

Kharâb is an adjective meaning "broken" or "ruined." Farsi frequently builds compound verbs using shodan (to become) to show a change of state. So kharâb shod literally translates to "became broken," which is the natural way to say something stopped working on its own.