The whole phrase is deliberately ungrammatical. I think the idea is that although someone may not speak entirely grammatically correct English, they may possess innate common sense or wisdom that book-learning and education cannot give you. It makes the expression seem more profound. Consider the grammatically correct version of the phrase: If it isn't broken, don't fix it. It's nowhere near as powerful.

It is because this is another set phrase. Also in the past tenses were not used the same way as they ate today , so sometimes people would use "broke" as the past participle: This wach is broke. However I am also not certain if ot could be in relation to which country it is from. Traditionally many past participles had "en" on the end, the "en" suffix is an element of old English -- gotten forgotten, but in Britain they have decided to eliminate it , so they just say forgot and got for the past participle as well, while in America we retain the traditional way.

It is consciously "demotic" speech--the plain speech of "the people." The mental picture behind it is of some sophisticated, overeducated city person, walking into a garage and asking for some unnecessary piece of fine tuning to be done on his car. We imagine some wise old auto mechanic with only a high school education but rich in life experience, saying "If it ain't broke, don't fix it." The use of "broke" instead of "broken" goes along with the use of "ain't" instead of "isn't."

اگر اونو شكسته نبود كه اونو تعمير نكن

Hello :) The use of deliberately non-standard English gives a great deal of power to this statement, for two reasons: - It makes the sentence stand out. If I am speaking ( as I usually do!) in correct, grammatical, standard English and I suddenly say 'If it ain't broke, don't fix it', this is a linguistic signal that these words are different. It makes it obvious that I am using a figure of speech/quote/cliche/set phrase of some kind, and it is immediately clear that these are not 'my words'. It's a signal that I'm using a sort of metaphor to illustrate my point, rather than a neutral statement to be taken literally. 2. As Paul says, the choice of grammar which sounds unsophisticated and old-fashioned reinforces the message. The use of this unpretentious language seems to hark back to an older, simpler era when basic common sense was what counted most. We say this expression of 'If it ain't broke' as an encouragement to use common sense, and the language it uses does a lot to strengthen this message.