1. A sheliach tzibbur who erred and skipped one of the blessings [of Shemoneh Esreh], but when he is reminded he knows to which point he must return, he should not be removed [from his position]. If, however, he skipped “the blessing concerning the heretics - the Malshinim,” he should be removed [from his position] immediately because it is possible that he is a heretic - an Apikorus. But if he if he began that blessing, but erred, he is not to be removed [from his position.]
2. If a sheliach tzibbur erred and does not know to which point he must return, another person should replace him. And he [the replacement] returns to the beginning of the blessing at which [his predecessor] erred. This is if the error [of the sheliach tzibbur] was in [one of] the first middle blessings. And if [the error] was in one of the first three blessings, [his replacement] must start from the beginning [of Shemoneh Esreh]. And if [his error was] in [one of] the last three, [his replacement] must begin with the blessing Retzeh,
3. In all situations in which an individual is required to repeat [his whispered Shemoneh Esreh due to a mistake], a sheliach tzibbur [who made a similar mistake during his audible repetition of Shemoneh Esreh] must start again [from the beginning] if he made the same mistake. Except for Shacharit of Rosh Chodesh, he is not required to repeat Shemoneh Esreh, because this would inconvenience the congregation because the Mussaf Service I sstill coming up and there he will mention Rosh Chodesh. If, however, he recalled his error before he completed Shemoneh Esreh, he should return to the blessing of Retzeh and it is not considered an inconvenience for the congregation . RM”A: There are those who say that if he makes a mistake in Shacharit of Shabbos, or of the festivals, the rule is the same as Rosh Chodesh, and this is our Minhag,
4. If a sheliach tzibbur erred in his recitation of the whispered Shemoneh Esreh he is never required to repeat it in a whisper, because [waiting for him] would inconvenience the congregation. Instead, he should rely on the Tefila that he will say out loud. [The above applies] provided he did not err in the first three blessings, because if he errs in those, he must return [to the beginning], just as an individual must do.