Mehaničko oštećenje je u servisnom izveštaju.

Because oštećenje is a neuter singular noun, and the adjective has to agree with it in gender, number, and case.

• mehanički = masculine
• mehanička = feminine
• mehaničko = neuter

So:

• mehanički kvar = a mechanical defect
• mehanička greška = a mechanical error
• mehaničko oštećenje = mechanical damage

Here, oštećenje is neuter, so the adjective must be mehaničko.

It is in the nominative singular.

In this sentence, mehaničko oštećenje is the subject, so nominative is the normal case to use.

• oštećenje = nominative singular
• mehaničko matches it in nominative singular neuter

So the structure is basically:

Mehaničko oštećenje + je + u servisnom izveštaju
subject + is + location

Because je is a clitic in Serbian. Clitics usually go in second position in the sentence, or more precisely after the first stressed unit.

Here, the first unit is the whole noun phrase Mehaničko oštećenje, so je comes after it:

• Mehaničko oštećenje je u servisnom izveštaju.

You do not normally say:

• Mehaničko je oštećenje u servisnom izveštaju.

That sounds unnatural here.

This second-position rule is very important in Serbian word order.

Because u can take different cases depending on the meaning:

• u + locative = location, being in something
• u + accusative = movement into something

In this sentence, the damage is in the report, not moving into it, so Serbian uses the locative:

• u servisnom izveštaju = in the service report

That is why both words change form:

• servisni → servisnom
• izveštaj → izveštaju

Their dictionary forms are:

• servisni = service-related
• izveštaj = report

In the sentence, they appear in the locative singular because they follow u with a location meaning:

• servisni → servisnom
• izveštaj → izveštaju

So:

• dictionary form: servisni izveštaj
• in the sentence: u servisnom izveštaju

Here it is best understood as in.

With documents, Serbian often uses u where English might say in or sometimes conceptually on, depending on context. In this sentence, u servisnom izveštaju means that the mechanical damage is mentioned/listed/recorded in the service report.

So even though English speakers may sometimes think of information as being on a report, Serbian naturally uses u.

There is no separate word for the because Serbian does not have articles like English a/an/the.

So servisni izveštaj can mean:

• a service report
• the service report

Which one is meant depends on context.

In this sentence, English will often translate it as the service report because it sounds like a specific report is already known.

Yes, Serbian word order is fairly flexible, but not completely free.

This sentence could also be rearranged for emphasis, for example:

• U servisnom izveštaju je mehaničko oštećenje.

That puts more focus on where it is.

However, the clitic je still tends to stay in second position relative to the first unit of the sentence.

So word order can change, but clitic placement still matters.

A rough guide:

• č as in church, but firmer
  
  • mehaničko
• ć is a softer sound than č, something like a very soft ch/t sound
  
  • oštećenje
• š = sh
  
  • oštećenje
• nj sounds like the ny in canyon
  
  • oštećenje
• j is pronounced like English y
  
  • izveštaju

A rough English-style approximation of the whole sentence could be:

meh-ha-NEECH-ko osh-TEH-che-nye ye oo sehr-VEES-nom eez-VEHSH-ta-yoo

That is only an approximation, but it helps get close.

Yes. They are regional standard variants of the same word.

• izveštaj = Ekavian Serbian
• izvještaj = Ijekavian form

They both mean report.

So depending on the variety of Serbian you are learning, you may see either:

• u servisnom izveštaju
• u servisnom izvještaju

Both are correct in their respective standards.

Usually yes, but it is a noun meaning damage or damage/deterioration to something.

It is often used for physical damage:

• oštećenje vrata = damage to the door
• mehaničko oštećenje = mechanical damage
• oštećenje motora = damage to the engine

So in this sentence, it refers to a specific kind of physical damage, not just a vague problem.