Zevachim 15A

אפשר לתקונה או לא אפשר לתקונה?

The Talmud asks: If the blood was conveyed by hand, is it possible to correct it by conveying it again properly, or is it not possible to correct it, and the offering is disqualified permanently?

תא שמע: קבל הכשר ונתן לפסול ⁠– יחזיר לכשר;

The Talmud suggests: Come and hear proof from the aforementioned Mishnah: If a priest fit for Temple service collected the blood in a vessel and gave the vessel to an unfit person standing next to the altar, the latter should return it to the fit priest. Apparently, even after the blood is conveyed in an inappropriate manner, it can be corrected.

ונהי נמי דיחזור הכשר ויקבלנו, אי סלקא דעתך לא אפשר לתקונה ⁠– איפסלא לה!

And though one can indeed explain that the fit priest should then receive it from him, as posited above, if it enters your mind that if the blood is conveyed incorrectly it is not possible to correct it, the offering was already disqualified when the priest gave the blood to the unfit person. Taking it back is of no consequence.

מי סברת דקאי זר גואי?! לא; דקאי זר בראי.

The Talmud rejects this inference: Do you maintain that this is referring to a case where the non-priest is standing inside, between the fit priest and the altar? No, it is a case where the non-priest is standing outside, farther away from the altar than the priest. Therefore, when the priest gave him the blood, he was not conveying it toward the altar at all; he was moving it farther away from the altar.

איתמר, אמר עולא אמר רבי יוחנן: הולכה שלא ברגל ⁠– פסולה. אלמא לא אפשר לתקונה.

It was stated: Ulla says that R' Yoḥanan says: Conveying the blood not by foot renders the offering unfit. Apparently, it is not possible to correct it, as otherwise R' Yoḥanan would have merely stated that it is not considered conveying, as in his earlier statement (14b).