Se la serratura si blocca, chiamo il tecnico.

This is very normal in Italian.

In a real or likely condition, Italian often uses:

• se + present indicative
• present indicative in the main clause as well

So Se la serratura si blocca, chiamo il tecnico means something like:

• If the lock gets stuck, I call the technician
• If the lock jams, I’ll call the technician

The Italian present here can express:

• a usual reaction
• a planned response
• something that will happen when the condition occurs

Italian often uses the present where English prefers will.

You could also say Se la serratura si blocca, chiamerò il tecnico, and that would sound more explicitly future-oriented.

Si blocca comes from the verb bloccarsi.

• bloccare = to block, to jam something
• bloccarsi = to get blocked, to jam, to get stuck

So la serratura si blocca means the lock gets stuck or jams.

The si is part of the pronominal/reflexive form bloccarsi. In English we usually do not say the lock blocks itself, but Italian often uses this kind of structure for things that happen to the subject.

Compare:

• Blocco la porta = I block the door
• La serratura si blocca = The lock gets blocked / jams

So here si does not really mean itself in a literal English sense. It is just how the verb works in this meaning.

In this sentence, the relevant dictionary form is bloccarsi.

• blocca by itself could come from bloccare
• but because the sentence has si blocca, the full verb is bloccarsi

So if you want to learn the exact expression used here, learn:

• bloccarsi = to get stuck, to jam

That will help you recognize similar sentences such as:

• La porta si blocca
• Il computer si blocca
• L’ascensore si blocca

Italian uses articles more often than English.

La serratura means the lock, and in Italian it is completely natural to include the article even where English might sometimes be less explicit.

Here it refers to the lock in question, the one relevant in the situation. Italian generally wants the article with concrete nouns like this.

So:

• la serratura = the lock
• not just serratura

Without the article, the sentence would sound incomplete or unnatural in standard Italian.

For the same basic reason: Italian normally needs an article before a singular count noun used this way.

So:

• chiamo il tecnico = I call the technician

Without il, chiamo tecnico is not correct standard Italian.

Also, tecnico here means a technician, repair person, or specialist, depending on context. Italian often uses the article with professions and roles when they are direct objects.

Yes.

Se la serratura si blocca, chiamo il tecnico can mean:

• whenever the lock gets stuck, I call the technician
• if the lock gets stuck, I’ll call the technician

So the sentence can be read as:

• a habitual response
• a standing plan
• an immediate future action

The exact meaning depends on context.

If you want to make the future meaning more explicit, you can say:

• Se la serratura si blocca, chiamerò il tecnico

If you want to stress habit, context usually does the job, though you could also say something like:

• Ogni volta che la serratura si blocca, chiamo il tecnico

Because this is a normal, real condition.

After se, Italian usually uses the indicative for ordinary factual or possible conditions:

• Se piove, resto a casa
• Se arriva, ti avviso
• Se la serratura si blocca, chiamo il tecnico

The subjunctive is not the standard choice in this kind of if clause.

A very important pattern to remember is:

• real/likely condition: se + indicative
• more hypothetical pattern: often se + imperfect subjunctive with conditional

For example:

• Se la serratura si bloccasse, chiamerei il tecnico
  = If the lock were to get stuck, I would call the technician

So your original sentence is the normal real-condition pattern.

Yes.

Italian allows some flexibility. You can also say:

• Chiamo il tecnico se la serratura si blocca

This means the same thing. It may sound slightly less like a setup-and-result structure and more like a straightforward statement.

You may also hear:

• Se si blocca la serratura, chiamo il tecnico

That is possible too. It puts the verb before the subject inside the se clause. The meaning stays the same, though the emphasis shifts a little.

The most neutral version is probably the original:

• Se la serratura si blocca, chiamo il tecnico

It is standard and very common when the se clause comes first:

• Se la serratura si blocca, chiamo il tecnico.

If the main clause comes first, Italian often omits the comma:

• Chiamo il tecnico se la serratura si blocca.

So the comma is not about grammar in the strictest sense as much as normal punctuation and readability.

Not with the same meaning.

• si blocca = gets stuck, jams
• viene bloccata = is blocked by someone or something

So:

• La serratura si blocca suggests the lock malfunctions or jams
• La serratura viene bloccata suggests an outside force blocks it

The original sentence is talking about a lock that stops working properly, so si blocca is the natural choice.

Not necessarily.

Il tecnico is broader than locksmith. It usually means:

• technician
• repair person
• specialist

In context, it could be the person who handles the lock problem, but the word itself does not specifically mean locksmith.

If you specifically wanted locksmith, the usual word would be:

• il fabbro

So the sentence with il tecnico sounds more general, like calling a maintenance technician or service professional.