A new chapter (3)! With a new mishnah. Which continues the topics of chapter 2. If those who are disqualified from doing the Temple service do the slaughter of the offering, the offering is still valid. That is, assuming their intentions are correct, and so on, throughout their practice. What if collecting/receiving the blood is done by someone who is qualified, but hands it off to the disqualified person? What if blood spills to the floor? What if the blood was conveyed to the wrong place? The key element to making sure that the worship is valid is the capacity to revisit it and fix what has gone wrong - as long as there is "dam ha-nefesh." Also, the case of a ritually impure person who places his hand into the courtyard of the Temple - even though he hasn't entered fully - may require lashes (it's a machloket). In the case of the person who has had tzara'at and isn't yet purified, there may be leniency. Of course, the Gemara counters with examples why the leniency would not apply (until the Gemara specifies this impurity as being different).