Chapter 6! With a new mishnah - Is the status of the altar as if it's fully in the north, or only on the northerly portion of the altar itself? Keep in mind that being slaughtered in the north is essential to the sacrifice - namely, for it to be valid. At least, for the kinds of offerings that must be slaughtered in the north to be valid. One solution to the dispute, of course, is the fact that the offerings themselves had different requirements. Also, the Gemara looks for the sources for the northerly location. Plus, where the altar actually stood (not so simple), and the differences between what was relevant for the inside and outside. The details of the options of the antechamber vs. the main chamber are also essential here. All with an eye to the north.