Redensartenindex has no entries for "reparieren" or "beheben", which is how they translate fixen², incidently.

"Brechen" is not metaphoric and unlikely to lead to good results. The index only has zu Bruch gehen. Kaput has no entry either.

Without idiomaticity one might say,

Fass das nicht an, bevor es noch kaput / zu Bruch geht

Interestingly, ain't seems to begin as a contraction of am not, but it has a side of have not: “As a contraction of have not and has not, ain't derives from the earlier form han't, which shifted from /hænt/ to /heɪnt/, and underwent h-dropping in most dialects.” (https://en.wiktionary.org/wiki/ain't#Etymology)

We never say * ja wenn es nicht gebrochen hat. We say what doesn't kill me makes me stronger ("was mich nicht tötet, macht mich stark").

It is obvious that English brook, the regular cognate to German brauchen, has largely passed out of usage. For example, "Can you break a twenty?" may belong here: can you do me a favour, if you could use a large bill, trade me your small change?, ie. brauchst du ...?

The meaning is conveyed by to break in (new shoes, a young horse), cp. German anbrauchen, more often anbrechen, but chiefly verbrauchen, never ever to be confused with verbrechen, Ehebruch, though Missbrauch is close and Willen brechen may said of horses.

In this view, there is only one plausible cognate to fixen, left to the imagination of inclined readers, which explains why there is no German cognate of the phrase in living memory. German Fixer "heroin junky" might relate to this.

In addition, the noun Ger. Brauch ("custom, tradition") presents problems. Traho as well as alt-her-ge-brachtes might suggest a relation to bringen, to say the least (compare hand-me-downs).

Therefore one might say:

Wenn es nichts bringt, dann lass es halt

Redensartenindex has no entries for "reparieren" or "beheben", which is how they translate fixen², incidently.

"Brechen" is not metaphoric and unlikely to lead to good results. The index only has zu Bruch gehen. Kaput has no entry either.

Without idiomaticity one might say,

Fass das nicht an, bevor es noch kaput / zu Bruch geht

Interestingly, ain't seems to begin as a contraction of am not, but it has a side of have not: “As a contraction of have not and has not, ain't derives from the earlier form han't, which shifted from /hænt/ to /heɪnt/, and underwent h-dropping in most dialects.” (https://en.wiktionary.org/wiki/ain't#Etymology)

We never say * ja wenn es nicht gebrochen hat. We say what doesn't kill me makes me stronger ("was mich nicht tötet, macht mich stark").

It is obvious that English brook, the regular cognate to German brauchen, has largely passed out of usage. For example, "Can you break a twenty?" may belong here: can you do me a favour, if you could use a large bill, trade me your small change?, ie. brauchst du ...?

The meaning is conveyed by to break in (new shoes, a young horse), cp. German anbrauchen, more often anbrechen, but chiefly verbrauchen, never ever to be confused with verbrechen, Ehebruch.

In this view, there is only one plausible cognate to fixen, left to the imagination of the inclined reader, which explains why there is no German cognate of the phrase in living memory. German Fixer "heroin junky" might relate to this.

In addition, the noun Ger. Brauch ("custom, tradition") presents problems. Traho as well as alt-her-ge-brachtes might suggest a relation to bringen, to say the least (compare hand-me-downs).

Therefore one might say:

Wenn es nichts bringt, dann lass es halt