Explanation #1: Rashi explains that this pertains to cleaning out its innards.

Question: The Ri asks how he (Rebbi Eliezer) can bring a proof from there; perhaps there it is different, seeing as it was not possible to have performed it from the previous day?

Explanation #2: The Ri therefore explains that Machshirei Mitzvah after the Shechitah to which he refers is the burning of the fat pieces, for which one could have waited to perform at nighttime, yet it overrides Shabbos.

Support: And so it states in the Yerushalmi, where Rebbi Eliezer states 'The Emurim of the Korban Tzibur are a proof - which even though it is possible to wait until Motza'ei Shabbos. And what is the difference between the Machshirin after Shechitah ... ?

Implied Question: And when the Gemara then asks that one should also not Shecht it, even though it is not possible (to perform it earlier) ...

Answer: It nevertheless asks, having already proved that there is no distinction between whether it is possible or not, seeing as it permits the burning of the fat pieces.

Clarification: We need to say that Rebbi Eliezer thought that Rebbi Akiva was referring to the Haza'ah of the Korban Pesach, which is why he answered him that this is precisely what he was weighing up, with the intention of permitting it.

Clarification (cont.): Since the Gemara currently holds that Haza'ah of the Pesach is permitted.

Clarification (cont.): And Rebbi Akiva suggested to him that perhaps it is the other way round, because he thought that Rebbi Eliezer erred in what he taught him that it does not override Shabbos (See Maharsha).

Question: Why can we not learn that it overrides Shabbos from all of the other cases?

Answer: Because it is possible to perform the Mitzvah of eating T'rumah after Shabbos.

Question: Why should we think that, bearing in mind that whoever carries the Mei Chatas is Tamei and will therefore render it Tamei?

Answer: It speaks where he transported it in stone or marble vessels, which are not subject to Tum'ah.

Clarification: Only according to Rebbi Eliezer is there a distinction between fit and unfit.

Clarification (cont.): But Rebbi Akiva does not differentiate between them ...

Source: Since he says in the Mishnah 'Haza'ah will prove ... '.

Implied Question: And when Rebbi Eliezer says that Machshirei Milah override Shabbos ...

Answer: He must be speaking where they heated water on Erev Shabbos, which renders him fit.

Clarification: Nevertheless, he is Chayav Kareis, seeing as he could have Toveled, in which case they would have Shechted and sprinkled on his behalf.

Source: As we will learn shortly - 'Shochtin ve'Zorkin al T'vul-Yom', bearing in mind that the sun sets automatically (and no additional act is required)

Question: If we hold 'Shochtin ve'Zorkin al Tamei Sheretz, why does the Torah need to tell us that a Tamei cannot bring the Korban Pesach (See Maharam)? Why is it not obvious, seeing as it writes "Ish L'fi Ochlo" , which requires the person bringing it to be fit to eat it ...

Proof: As is evident in 'Keitzad Tzolin' (later 78:)?

Answer #1: The Rashba answers that the Torah finds it necessary to teach us that he is Chayav to bring Pesach Sheini, as we would otherwise say that he is Patur, since Pesach Sheini is a substitute for Pesach Rishon ...

Answer #1 (cont.): Because whoever is fit on Pesach Rishon, can bring iton Pesach Sheni, and whoever is not fit cannot ...

Proof: As we will say later with regard to the Chagigah, in 'Keitzad Tzolin' (Daf 80.)

Answer #2: Alternatively, the Torah needs to tell us that the Tzibur can bring it be'Tum'ah, as the Gemara Darshens "Ish ki Yih'yeh Tamei" - Ish Nidcheh (an individual is pushed away) ve'Ein Tzibur Nidachin'.

Clarification: This means that if he is able to rectify himself (to be able to eat the Korban Pesach), but did not, this does not prevent him from eating it.

Clarification: But not if he is properly Tamei, which is no different than a sick person or an old man.

Refuted Explanation: Not like Rashi, who explains that when the Torah writes "Ish L'fi Ochlo", it means that this ideally speaking (Lechatchilah only).

Refutation #1: Bearing in mind that earlier (on Daf 61.) the Gemara established it even by Bedi'eved.

Refutation #2: And the Gemara concludes in 'Keitzad Tzolin', based on "Ish L'fi Ochlo", that the man must be fit to eat it.

Question: If so, asks the Riva, why did Rebbi Eliezer say earlier that an Areil who failed to perform B'ris Milah is subject to Kareis, seeing as he is fit to bring the Korban, only he did not rectify himself?

Answer: It is different there, since he is lacking an act on his body, in which case the Korban is considered 'she'Lo le'Ochlav'.

Implied Question: The reason the Gemara does not ask 'Hilch'sa li'Meshicha?'

Answer: Is explained in Perek Arba Misos (Sanhedrin, Daf 51:)

Clarification: The Tz'richusa is according to Rav Yehudah, to explain why he needs to rule in both cases like Rebbi Akiva ...

Clarification (cont.): Because if it was to explain Rebbi Akiva himself, it should also have added the casein 'Sh'tei ha'Lechem' (Menachos, Daf 96.) where the Gemara concludes 'K'lal Amar Rebbi Akiva'.

Question: Of what use is the fact that thirteen covenants were made with the Milah, now that there is an independent Pasuk for Machshirin (as Tosfos explained above)?

Answer: The Rashba therefore explains that, had Rav Yehudah not ruled like Rebbi Akiva with regard to Milah, he would have held completely like Rebbi Eliezer ...

Answer (concl.): And with regard to Pesach he rules like Rebbi Akiva - specifically Lehachmir mi'de'Rabbanan, that Machshirin should not override Shabbos, but not by Milah itself, on which thirteen covenants were made.