We have a house with a lot of 2-prong outlets I'd like to replace. They're all fed by conduits. Multiple people (in real life and online) have told me that replacing them is easy: "Just fish the new cable through the conduit," or, "tie the old cable to the new cable and pull it out."
However, I can't do either of these things if I don't know which conduit-openings belong to the same length of conduit. The conduit out of all of the electrical boxes simply go up or down, and I don't see any of it in the basement or attic (except out of the panel). To make matters worse, almost all of the outlets in the house are on a single circuit, so they could be tied together in almost any way.
So, how can I tell where the ends of the conduit are so I can rewire my house?