If it ain't broke, don't fix it

Possible interpretation: If something is not faulty or damaged, don't try to repair it.

Note: ain't (verb): [contraction of] am not, are not, is not | broke (adj.): broken; damaged; faulty | fix (verb): repair; mend | The British English equivalent of this saying is: "Let well alone."

Origin: American businessman Bert Lance (born 1931) writing in Nation's Business (1977).

Variety: This is typically used in American English but may be used in other varieties of English too.