Wir helfen mit, soweit unsere Reparaturkenntnis reicht.

Because the verb here is the separable verb mithelfen.

• mithelfen = to help out, to lend a hand
• In a normal main clause, the finite verb goes in position 2, and the separable prefix moves to the end.

So:

• infinitive: mithelfen
• main clause: Wir helfen mit.

This is the same pattern as:

• ankommen → Der Zug kommt an.
• einkaufen → Ich kaufe ein.

helfen simply means to help.

mithelfen usually means to help out, to join in helping, or to contribute to a shared effort.

So Wir helfen mit suggests something like:

• we’re pitching in
• we’re helping as much as we can
• we’re taking part in the effort

That little mit- often gives the idea of participating along with others.

That’s a good observation. Yes, helfen normally takes a dative object:

• Wir helfen dir. = We help you.

But mithelfen is often used without naming the person or thing being helped. In that case it just means to help out in general:

• Kannst du mithelfen?
• Alle haben mitgeholfen.
• Wir helfen mit.

So there is no missing object here; the sentence is complete as it stands.

Here soweit means something like:

• as far as
• to the extent that
• insofar as

So soweit unsere Reparaturkenntnis reicht means as far as our repair knowledge goes or to the extent that our repair knowledge is enough.

It is not about physical distance here. It introduces a limit: we will help, but only within the limits of what we know how to repair.

Because soweit introduces a subordinate clause, and in German subordinate clauses the finite verb goes to the end.

Main clause:

• Wir helfen mit

Subordinate clause:

• soweit unsere Reparaturkenntnis reicht

This is the same pattern you see after words like weil, dass, wenn, obwohl, etc.:

• ..., weil er keine Zeit hat.
• ..., wenn sie kommt.
• ..., soweit unsere Reparaturkenntnis reicht.

Because German normally uses a comma to separate a main clause from a subordinate clause.

So:

• Wir helfen mit, soweit unsere Reparaturkenntnis reicht.

The comma is required here.

Both are possible, but they feel slightly different.

• Reparaturkenntnis (singular) treats the idea as one overall body of knowledge: our repair know-how
• Reparaturkenntnisse (plural) emphasizes separate skills or areas of knowledge: our repair skills/knowledge

In this sentence, the singular sounds like an abstract mass noun, similar to:

• unsere Erfahrung
• unsere Fachkenntnis
• unser Wissen

So unsere Reparaturkenntnis reicht means our repair knowledge is sufficient / extends far enough.

That said, many speakers might also naturally say Reparaturkenntnisse in everyday usage.

Because Kenntnis is a feminine noun: die Kenntnis.

Here it is singular and nominative, so the possessive adjective has to match that:

• masculine nominative: unser
• feminine nominative: unsere
• neuter nominative: unser
• plural nominative: unsere

So:

• unsere Kenntnis
• unsere Reparaturkenntnis

Even though the meaning is our knowledge, the grammar is determined by the gender and case of Kenntnis.

The verb reichen often means to be enough, to suffice, or literally to reach.

In this sentence it has the idea of extending far enough or being sufficient:

• Das Geld reicht. = The money is enough.
• Meine Geduld reicht nicht mehr. = My patience is running out / is no longer enough.
• Soweit unsere Reparaturkenntnis reicht = As far as our repair knowledge is sufficient

So reicht expresses a limit.

Here it is correctly written as one word: soweit.

Why? Because it is functioning as a conjunction meaning insofar as / as far as.

Compare:

• soweit ich weiß = as far as I know
• soweit möglich = as far as possible
• soweit unsere Reparaturkenntnis reicht = as far as our repair knowledge goes

By contrast, so weit as two words is more likely when so and weit are being used more literally or separately, often with a physical or measurable sense:

• Es ist nicht so weit. = It’s not that far.
• Gehen wir schon so weit? = Are we going that far already?

Yes, it is understandable and grammatically fine. German often forms compounds very freely, and Reparaturkenntnis clearly means knowledge of repair / repair know-how.

Still, depending on context, some speakers might prefer alternatives such as:

• Reparaturkenntnisse
• Kenntnisse in Reparaturen
• Know-how bei Reparaturen
• technische Kenntnisse

So the original wording is valid, but it can sound a little formal or compressed because it is a compound noun.

Yes, but the nuance changes a bit.

• Wir helfen mit = We help out / we pitch in
• Wir helfen = We help

Without mit, the sentence is more general. With mit, it sounds more like joining in and contributing to a shared task.

So both can work, but mithelfen is a bit more specific in tone.

The sentence has two parts:

1. Main clause:
   • Wir helfen mit
2. Subordinate clause:
   • soweit unsere Reparaturkenntnis reicht

So the pattern is:

• [main clause], [subordinate clause]

And inside those parts:

• Wir = subject
• helfen = finite verb
• mit = separable prefix

Then:

• soweit = subordinating conjunction
• unsere Reparaturkenntnis = subject of the subordinate clause
• reicht = finite verb at the end

So it is a very typical German combination of a main clause plus a verb-final subordinate clause.