Clockwork and Cryptography: Angelmaker Code Hints, Part 4

Welcome back! Before you read this hint, make sure you take a look at the preceding ones:

Hint 0/1
Hint 2
Hint 3

We've gotten to the point where the things I point out as hints may be old news to you. On the other hand, who knows? It's time to consider one of three (possibly four) features of this code that I'm going to call "non-core" - i.e., they modify the code's basic functionality to improve its comprehensiveness. I'm sure that the basic codebreaking literature addresses this (and maybe has a different term for it), but for my purposes, I'm going to define "comprehensive" as "the ability of a code to represent all elements of the plaintext as ciphertext." This code is about 98% comprehensive. For comparison, a non-comprehensive code might represent the plaintext

ATTACK AT DAWN, SIGNED PATTON

like this:

TTCK T DWN SGND PTTN

which is 1) not a very good code, and 2) unable to represent words such as "a" or "I". It's not as comprehensive as a Caesar cipher (95-100% comprehensiveness, depending on the plaintext) because there are letters in the original message - the vowels and the punctuation - which simply can't be written in the code.  (For interested parties: you could figure out the comprehensiveness of this code by adding up all the letter frequencies of A, E, I, O, and U and subtracting from 100.)

Assuming that you've figured out the basics of how the Angelmaker code works, I'm going to estimate its comprehensiveness at around 85%, depending on what you've realized about certain other features. You could definitely read the message(s) if you couldn't figure this bit out, but there would be some ambiguity. If you add in the feature I'm pointing out here, you'd be at around 88% - maybe as much as 90 or 91, although I haven't done the research. So: what's the deal with this?

Well?

In Hint 1, I think I pooh-poohed the idea of comparing the relative frequencies of each disk (and rightly so, as you'll probably have realized by now). Now I'm going to tell you to bring that strategy back. Where does that extra line appear? How often? Does it ever appear in the inner ring? How many sections (out of the total 12 outer + 6 inner  = 18) does it bisect? I'd also suggest that you just browse around here for a bit. Just sayin'. 

And there you go! That's three hints in one, for those keeping score at home. Oh...I only put in two? I'm so terribly sorry, I must be mistaken. Bwahahahaha. 

Have fun!

(Or for extra help, read the next hint here.)