Goodman Games

I just got the new hardcover supplement and I read through the whole Chained Coffin adventure and I can't figure out how the players are supposed to discover the solution to the wheel puzzle. It's an awesome add-in with all sorts of potential for interpretation and reasoning but as far as I can tell the only clue in the entire adventure is in the Bigginty's house which just gives the solution away without any understanding.

According to the module the players must align the symbols of Lusaahl, Shul and Earth but I don't see anywhere in the adventure where the players are supposed to learn the meaning of the glyphs. Did I miss something?