I like the 3-D printed model of what went wrong on the last page. A picture worth a lot of words.

Did anyone else having trouble scrolling through this in Acrobat Reader? PgDn and touchpad scroll both skip from page 2 to page 4 for me, then scrolling back up hits page 3 and skips to page 1. Scrolling down from page 3 took me as far as page 6.