Cathy- It has to do with where each of the chains ends at the top of the harp. In order to avoid crossovers in the chain around the second or third octave, they decided to cross the rods inside the column. I just finished rebuilding a Wurlitzer DDX(which will be up on my company web site soon if you want to see it) and the crossovers are even worse in that one. Most harps of that period had discs only up to O F. But this model had discs on OOG. So in order to do that and not have any crossovers in the chains, they reordered the rods. In that case the order looks like this: Again, write down the following letters at the top and bottom of a piece of paper and then draw a line from the letter at the bottom to the corresponding letter at the top.
F E D C B A G
D C E B F G A