Factor suculam movet quasi prelum nimis grave sit.

Because factor is in the nominative singular, and movet is third-person singular, so they go together as subject and verb: factor movet = the worker/agent moves.

A useful point for English speakers: not all Latin nominative singular nouns end in -us. factor is a third-declension noun, so its nominative singular is simply factor.

Because it is the direct object of movet. It is the thing being moved.

• movet = moves
• suculam = the ... being moved

The ending -am is the normal accusative singular ending for a first-declension noun.

Here quasi means as if or as though.

It introduces a clause of comparison/appearance:

• Factor suculam movet = the worker moves the device
• quasi prelum nimis grave sit = as if the press were too heavy

An important nuance: the speaker is not necessarily stating that the press really is too heavy. The clause tells you how the action appears or is being compared.

Because after quasi meaning as if, Latin often uses the subjunctive rather than the indicative.

• est would be a plain statement: it is
• sit is subjunctive: as if it were / as though it were

So sit shows that this is not being presented as a straightforward fact, but as an imagined or comparative situation.

Because grave agrees with prelum, which is neuter singular.

The adjective gravis, grave has these nominative singular forms:

• masculine/feminine: gravis
• neuter: grave

Since prelum is neuter, Latin uses grave:

• prelum grave = a heavy press

In this sentence, prelum is functioning as the subject of sit, so it is nominative.

A tricky point: prelum is a neuter second-declension noun, and in neuter nouns the nominative singular and accusative singular are often the same. So the form prelum could be either nominative or accusative just by itself.

You tell its role from the sentence:

• prelum ... sit = the press ... is/were
• grave also agrees with it as a predicate adjective

So here it is nominative in function.

nimis is an adverb meaning too, excessively, or overly.

It modifies grave:

• grave = heavy
• nimis grave = too heavy

So the sense is as if the press were too heavy.

Yes. The main clause is quite normal Latin word order:

• Factor = subject
• suculam = object
• movet = verb

That gives you a basic subject-object-verb pattern, which is very common in Latin.

Then the quasi clause comes after it. Latin word order is flexible, but this sentence is not unusually arranged.

There is no separate word for the or a/an in classical Latin. Latin normally does not use articles.

So:

• factor can mean the worker or a worker
• prelum can mean the press or a press

The context or the translation decides which is more natural in English.

Because English and Latin handle as if clauses differently.

In English, after as if/as though, we often use were:

• as if the press were too heavy

In Latin, present subjunctive can still be used for a situation that is simultaneous with the main verb:

• movet ... quasi ... sit = he moves ... as if it were ...

So even though sit is present subjunctive, idiomatic English may still use were. This is a translation habit of English, not a sign that the Latin is past tense.