Gemara

Version #1 (Rav): A Nazir must wave (the Zero'a and Lechem to become permitted to become Tamei and drink wine).

This is unlike Chachamim. They permit even without shaving, all the more so without waving! Rather, it is like R. Eliezer, who permits after all the actions;

One might have thought that since one gets atonement without waving, one is also permitted without waving. Rav teaches that this is not so.

Question (Beraisa #1): "Zos Toras ha'Nazir" - whether or not he has hands. (Just like a handless Nazir is permitted without waving, also one with hands!)

Counter-question: If so, the coming Beraisa should teach that shaving is not Me'akev, but a third Beraisa says that shaving is Me'akev!

Beraisa #2: "Zos Toras ha'Nazir" - whether or not he has hair.

(Beraisa #3 - Beis Shamai): If a Nazir's hair fell out, he need not pass a razor over his head;

Beis Hillel say, he must do so.

Ravina: Beis Shamai say that he need not, i.e. he must shave to become permitted, but he cannot.

Inference: Beis Hillel say that shaving permits him! Ravina holds like R. Pedas, who said that Beis Shamai and R. Eliezer said similar laws.

Question: To which teaching of R. Eliezer does R. Pedas refer?

Answer (Mishnah - R. Eliezer): A Metzora lacking a right thumb or big toe can never become Tahor;

R. Shimon says, it suffices to put (the blood and oil) on the place where the thumb or toe should be;

Chachamim say, it suffices to put them on the left thumb or toe.

Version #2 (Rav): The Nazir must wave (to become permitted).

This would be no Chidush according to R. Eliezer, who permits after all the actions. Rather, it is according to Chachamim.

Objection: Chachamim permit without shaving, all the more so without waving!

Answer (Beraisa #1): "Zos Toras ha'Nazir" - whether or not he has hands. (Just like waving is Me'akev a handless Nazir, it is Me'akev one with hands!)

Question (Beraisa #2): "Zos Toras ha'Nazir" - whether or not he has hair.

You cannot similarly explain that shaving is Me'akev a bald Nazir!

(Beraisa #3 - Beis Shamai): If a Nazir's hair fell out, he need not pass a razor over his head. Beis Hillel say, he must do so.

Answer (R. Avina): Beis Hillel say that he must, i.e. he must shave, but he cannot. Beis Shamai permit him without passing a razor.

R. Avina argues with R. Pedas.

Yoma 61b (Beraisa - Beis Shamai): If a Nazir's hair fell out, he must pass a razor over his head. Beis Hillel say, he need not. (This is unlike our version in Nazir.)

(R. Avina): Beis Shamai say that he must, i.e. he must shave, but he cannot.

Rishonim

Rambam (Hilchos Nezirus 8:5): A bald Nazir need not pass a razor over his head. Even though he has no hair or no hands, he offers his Korbanos and is permitted to drink and become Tamei. Once Zerikah of one of the Korbanos was done he is permitted, even though nothing was put in his hands and he did not wave. These matters are l'Chatchilah. They are not Me'akev.

Question #1 (Kesef Mishneh). This is not like either version of Beis Hillel or Beis Shamai! Even the lenient opinion requires passing a razor!

Answer #1 (Kesef Mishneh): The Rambam rules like Beis Hillel in the first version, for in the second version Ravina and R. Pedas disagree. Beis Shamai said that the Nazir need not pass a razor, i.e. he must shave to become permitted, but he cannot. Beis Hillel permit without passing a razor. They said 'he must do so' to show that he can be permitted.

Question #2: The Rambam (Hilchos Mechusarei Kaparah 5:1) rules like R. Eliezer, that a Metzora lacking a thumb or toe cannot become Tahor!

Question #3: R. Eliezer permits after all the actions. Beis Shamai say that he must shave to become permitted, but he cannot. R. Pedas said that Beis Shamai and R. Eliezer said similar laws. Surely, he refers to this teaching of R. Eliezer! Why did the Gemara ask, and answer that he refers to the Mishnah of a Metzora without a thumb?

Answer (to Question #3 - Lechem Mishneh): There are two independent arguments. (1) Is shaving Me'akev? (2) Is passing a razor over a bald head considered shaving? R. Eliezer permits after all the actions, i.e. shaving is Me'akev. This does not reveal his opinion about (2). Beis Shamai require shaving to become permitted, but he cannot. I.e. shaving is Me'akev, and passing a razor over a bald head is not called shaving. The Mishnah of a Metzora without a thumb shows that R. Eliezer explains the verse simply (literally). Likewise, he must truly shave. Passing a razor over a bald head does not help.

Answer #1 (to Question #2 - Lechem Mishneh): The Rambam rules like R. Eliezer, who explains the verse simply regarding Metzora and Nazir (like Beis Shamai). However, he rules like Chachamim, who learn from "Achar-Achar" that shaving a Nazir is not Me'akev. There is no Gezeirah Shavah regarding Metzora, so he rules that putting the blood on the Behonos is Me'akev.

Answer #2 (to Questions #1 and 2 - Radvaz): The correct text of the Rambam should say that a bald Nazir must pass a razor over his head, even though he has no hair. This is like Beis Hillel, according to Version #1.

Answer #3 (to Questions #1 and 2 - Tziyonei Maharan, brought in Likutim in Frankel Rambam): The Rambam rules like the text in Yoma, which is like the text in the Tosefta and Yerushalmi (or because in Nazir, the opinions in the Mishnah in Nega'im are switched - Tosfos Yom Tov Nega'im 14:9 DH v'Ein).

Answer #4 (to Question #2 - Keren Orah Nazir 46a DH Mimeila): The Gemara compared Taharas Metzora and Nazir according to the opinion that shaving is Me'akev a Nazir. We hold like Beis Hillel that it is not Me'akev.

Tosfos (Sanhedrin 45b DH Ein): The first Tana says that a Metzora without a right ear (or thumb or toe) can become Tahor only if he lost it before becoming Tamei.

Question (Birkas Rosh Nazir 46b DH Sham (1)): The Gemara equates Nazir and Metzora. We should likewise distinguish between a Nazir who became bald before or after accepting Nezirus. If so, what was the Gemara's question in both versions? We can say that he can become permitted if he was bald from the beginning, but not if he became bald after accepting Nezirus!

Answer (Birkas Rosh): "Zos Tihyeh Toras ha'Nazir" teaches that Nezirus takes effect on anyone, even if he has no hair or hands. It follows that Beis Shamai and Beis Hillel argue about a Nazir who was bald from the beginning, yet one of them says that he cannot become permitted.

Question: The Gemara says that just like a handless Nazir need not wave, also one with hands. It is more reasonable to say that waving is Me'akev a handless Nazir, for Kol she'Einah Ra'uy l'Bilah Bilah Me'akeves Bo!

Answer: R. Nesan'el (in Shitah Mekubetzes 46): It could have said 'Al Kapav'. "Al Kapei ha'Nazir" teaches that this suffices for any Nazir, even if he has no hands.