The screen called Slide 3 displays an image uploaded as slide4.jpg. Its two hotspots sit side by side in the right half of the picture, back to Slide 2 first and then on to Slide 4. A screen in Connect-A-Sketch had a name of its own, separate from the file behind it, and the order of the tour lived in the links rather than in the file names.
The frame above is drawn at the original proportions. Each dashed box sits where the 2009 hotspot sat and links to the same screen it did then, so the tour can still be walked end to end.