לרפואת שרה לאה בת רבקה
The gemara [Pesachim 96] learns that just as the Korban Pesach requires ביקור ["examination"] 4 days previous to being brought as a korban, so too does the Korban Tomid require ביקור 4 days in advance. The obligation of ביקור applies to Pesach Mitzrayim and Pesach Doros equally:
In Succah  R' Yose says that if one shechts a Tomid that is not מבוקר on Shabbos he is חייב חטאת. Tosfos adds that this is talking even about an instance where a מום is not found afterwards and the animal is a תם.
Now why is ביקור necessary? The answer is because we are searching for a מום [see Menachos 49b with Rashi and numerous other places]. So if the whole purpose of the ביקור is to find a מום [which would forbid one to bring the animal as a korban as we see in Temurah 6] then why if the animal is found to be a תם is he חייב חטאת?? The entire tachlis of the ביקור was to see if there is a מום and there wasn't, so what is the problem??
Another question on Tosfos: The gemara in Pesachim [71b] says that if one shechts an animal and it is found to be a בעל מום then he is חייב. Rashi says that he is not אנוס because he should have performed ביקור. Yet, we see that he is only חייב if the animal is a בעל מום, implying that if the animal is a תם then he is not חייב anything - even if he didn't perform ביקור. That is not like Tosfos says??!