Daf Yomi - Yoma 42 - Comparing Porah Adumah to the Seeing of the Negoim

There is one opinion in the Gemora that the shechita of the porah adumah cannot be done by a yisroel. The Gemora asks from the concept that is learned that shechita is not considered an avodah and hence would be kosher with a yisroel. The Gemora answers that this is similar to the seeing of נגעים. Just like there, it must be done by a kohen, and only a kohen can pronounce that the person has a נגע and therefore טמא, even though it is not an avodah, so too by the shechita of the porah adumah, it must be performed by a kohen. Tosfos Yeshanim comments that according to this opinion, the kohen must be wearing his בגדי כהונה when he does the shechita.

The Mishna in פרה states that the shechita would be פסולה if the kohen would not be wearing his בגדי כהונה or if he would not have washed his hands and feet beforehand like any other avodah. The Steipler Gaon (Minachos 1) asks that this is not true by the seeing of נגעים? There, it is not necessary to wear the בגדי כהונה? He is forced to say that the Mishna is referring to the avodos after shechita, however by the shechita, he would not need to wear the בגדי כהונה. This is contrary to the Tosfos Yeshonim.

It is interesting to note that the Tiferes Yisroel in his introduction to Kodoshim seems to hold that the kohen must wear his בגדי כהונה when he is looking at a נגע. (It would seem that ultimately, he does not hold of this למעשה.)

Rav Moshe Mordechai Shulzinger (זבחים לו) says that according to the Steipler, one would wonder what the din is regarding a חלל (the son of a a kohen who married a divircee) by the shechita of the porah. The Rambam holds that a חלל is prohibited to look at a נגע and decide if it's טמא or not, even though he could perform a regular avodah (בדיעבד), but a kohen with a blemish would be allowed. This is the exact opposite of what the halacha is by a regular avodah. What would be the din by the porah adumah according to those that say that a kohen is needed? Could a בעל מום perform the shechita?