JMNT(i)
15 "Now if your brother should make a mistake (or: = your fellow believer may fail to hit the target for which he is aiming; or: your group member should be erring or sinning) [later MSS add: unto you; (= do you wrong)], humbly go [to him and] test it (or: bring convincing proof about it, laying the matter bare) between you and him alone. If he can listen and should be hearing you, you made gain and profit for your brother.
16 "Yet should he not listen [to you], take still one or two [others] along with you, so that 'upon [the] mouth of two or three witnesses (folks providing evidence) every thing that is said (every gush-effect; each result of the flow [of conversation or outbreak]) can be established and made to stand.' [Deut. 19:15]
17 "Now if he should put his hearing aside from (= disregard and refuse to hear) them, speak to the called-out community. Yet, if he should also put his hearing aside from (or: disregard) the called-out community, let him continue being with you (or: among you folks), just as (in the same manner as) the person of the ethnic multitudes (or: nations; pagans) and the tax collector [continue with you]. [comment: consider the behavior of Jesus with "sinners" and tax collectors; recall that these get into the kingdom before the religious; consider the place of the ethnic multitudes in relation to the good news]