De monteur heeft het spatbord vastgezet en ook het voorste wiel gecontroleerd.

This is the present perfect in Dutch, used very much like English has fastened / has checked.

• heeft = has
• vastgezet = fastened/secured
• gecontroleerd = checked

So the structure is:

subject + auxiliary + rest of sentence + past participle(s)

Here:

• De monteur = the mechanic
• heeft = has
• het spatbord vastgezet = fastened the mudguard/fender
• en ook het voorste wiel gecontroleerd = and also checked the front wheel

Dutch often uses this tense for completed actions, just as English does.

Dutch main clauses usually follow the V2 rule: the finite verb goes in the second position.

So in:

De monteur heeft het spatbord vastgezet ...

the finite verb is heeft, and it comes second, right after the subject De monteur.

This is one of the most important Dutch word-order rules. Even when the sentence gets longer, the conjugated verb still tends to stay in second position in a main clause.

In a Dutch main clause with a perfect tense, the auxiliary verb comes near the front, and the past participle(s) go toward the end.

So the pattern is:

subject + finite verb + other information + participle(s)

That is why you get:

• heeft near the beginning
• vastgezet and gecontroleerd near the end

This often feels unusual to English speakers, because English keeps the participle closer to has/have.

This comes from the separable verb vastzetten.

That verb is made up of:

• vast = fast, fixed, tight
• zetten = to put/set

In the past participle of a separable verb, ge- goes between the prefix and the verb stem:

• vastzetten → vastgezet
• compare: opbellen → opgebeld
• compare: aanzetten → aangezet

So vastgezet is the normal participle form of vastzetten.

They are formed according to two different verb types.

1. controleren is a normal, non-separable verb
   → past participle: gecontroleerd

2. vastzetten is a separable verb
   → past participle: vastgezet

So:

• ordinary verb: ge- usually goes at the front
  controleren → gecontroleerd

• separable verb: ge- goes between prefix and stem
  vastzetten → vastgezet

That is why the two participles look different.

Because spatbord and wiel are het-words.

In Dutch, singular nouns take either:

• de
• or het

You usually have to learn this with the noun.

So:

• het spatbord
• het wiel

Since both are singular het-words, the sentence uses het for both.

This is because Dutch adjectives usually take -e when they come before a noun with a definite determiner such as de, het, dit, dat, mijn, and so on.

Here we have:

• het ... wiel
• adjective: voorste
• noun: wiel

So the adjective gets the ending -e:

• het voorste wiel = the front wheel

Compare:

• een voorwiel = a front wheel
• het voorste wiel = the front/frontmost wheel

Also, voorste means something like front or frontmost, not just the basic direction word voor.

There are two separate things going on here.

First, wiel is a noun, and it is a het-word, so you need het wiel, not de wiel.

Second, voorste is an adjective meaning front/frontmost. It describes the wheel:

• het voorste wiel = the front wheel

You cannot use voor directly in front of wiel in the same way here. Dutch needs the adjective form voorste.

Here ook means also and is adding the second action/object:

• the mechanic fastened the mudguard
• and also checked the front wheel

Placing ook before het voorste wiel makes it attach naturally to that second part of the sentence:

... en ook het voorste wiel gecontroleerd

This is a very normal position. Dutch word order with words like ook can vary a bit depending on emphasis, but this placement is clear and natural.

Because Dutch, like English, can leave out repeated material when two parts are joined by en and share the same subject and auxiliary.

Full version: De monteur heeft het spatbord vastgezet en heeft ook het voorste wiel gecontroleerd.

Shorter version, which is what your sentence uses: De monteur heeft het spatbord vastgezet en ook het voorste wiel gecontroleerd.

Both are understandable, but the shorter version is more natural because heeft does not need to be repeated.

Not without changing the meaning or structure.

In this sentence, each participle belongs to its own object:

• het spatbord vastgezet
• het voorste wiel gecontroleerd

So the matching is important:

• the mudguard was fastened
• the front wheel was checked

If you moved the participles around carelessly, it could sound confusing or suggest the wrong thing was fastened or checked.

Dutch often keeps each object close to the participle that belongs to it, especially when there are two completed actions in one sentence.

Yes, that is a good basic way to understand it.

• en = and
• ook = also

So:

... en ook het voorste wiel gecontroleerd = ... and also checked the front wheel

The exact emphasis may vary a little depending on context, but and also is a very good interpretation here.

A useful pattern is:

Subject + hebben/zijn + object + past participle + en ook + object + past participle

For example:

• De monteur heeft het spatbord vastgezet en ook het voorste wiel gecontroleerd.
• De leraar heeft de toets nagekeken en ook de fouten uitgelegd.
• Zij heeft de deur gesloten en ook het licht uitgezet.

The key ideas are:

1. the finite verb goes in second position
2. the participles go toward the end
3. repeated heeft can be omitted in the second coordinated part if it is the same auxiliary and subject