Sag (update 4)

At this point, the sag was almost fixed:

You can still see a little bow in the floor, but it is much less than the 4.5 inches it was before.

Notice that the rest of that wall (at the top of the stairs) is now missing!

You’ll notice that the radiator didn’t move as much as I would have liked, but the top point is about and inch closer to the outer wall than it was before.