Going by the second definiton of an Amen Chatufa in Shulchan Aruch OC 124:8, i.e. saying Amen before the Beracha one is responding to is finished - is it possible to repair this or has the opportunity been lost? I.e. if one realises one did it, and then says Amen again (still in time to not be an Amen Yetoma - an Amen said too late), has one said Amen?
1 Answer
In the Sefer נוטרי אמן חלק ב פרק ז footnote ג (a full sefer on Amen!), he states that if someone responds with an Amen Chatufa (or Yetoma), it’s as though they haven’t answered amen to the bracha, and it doesn’t count.
Although I haven't seen him address if it's possible to repair an amen katufa, logically we can ask the same question by brachot (which is more stringent in the fact that Hashem's name is involved). Where if one says a bracha too early, i.e. saying brachot kriat shema before Alot Hashachar, etc (where the bracha is not good), can one say the bracha again at the correct time later? The answer would seem (and haven't seen anyone disagree) that one is able to do so, since he still has the ability to say the bracha at the correct time (we don't punish the person, and he should say baruch shem etc).
The same in regards to answering amen, one can answer amen even if he won't hear the end of the bracha, as long as you know which bracha is being said and heard certain important words which would be מעכב, as stated by Rav Ovadia in Halichot Olam 1:195, and also brought down in Shulchan Aruch O.C 215:2 with commentaries there.
Therefore if one says amen and there is still time for it not to be an Amen Yetoma, one can still answer amen.