Thanks AJ, and happy 75th birthday to Jim Sanborn.

Pretty much what I said before in reply to this thread, I think. The most interesting questions will get swatted away by Ed with "that's a Jim question" or "this is a Jim project from start to finish".

Let's put it again in different ways ...

Scheidt has one version of “how long it was supposed to take”: he has consistently stated on several separate occasions that it was intended to take 5, 7 or 10 years. 

Sanborn has at least four different stories: (a) a couple of weeks, a matter of weeks, the first few months; (b) a century, into or through the 21st century; (c) the CIA “will never figure it out” and it “might never be deciphered without the knowledge that [former CIA director] Webster has”; and (d) effectively, he will decide how long it will take: he will “release this hidden information at a rate commensurate with its importance, and at the time of my choosing so as to prolong the experience of discovery.”

Q for Ed: why are these answers of Jim and Ed different? could Jim have made some further changes which, intentionally or unintentionally, have made solution in the intended way effectively impossible? people are starting to wonder about this now 24 of 97 plaintext letters have been released. if it was supposed to take 5-10 years with 0 of 97 plaintext letters known, has something gone wrong? or are you still confident K4 has been "encrypted correctly"?

The working assumption is we're supposed to derive the encryption method of K4 from, most likely, statistical properties of the K4 ciphertext. if the would-be solver is more "artistic", perhaps they use more of the context of the metal sheets, or the context in the courtyard.

in 2007 - message 6886 - Ed to Elonka: K4 uses a system "unknown to anyone on the planet"
in 2013 - message 14984 - "Ed stated he didn’t recall that conversation [about "unknown to anyone on the planet"], and back-pedaled out of saying anything more."

Q for Ed: can you provide further clarification on that? If it is truly a new system, do you not think it's a hopeless task to determine the algorithm with just 97 letters of ciphertext, as for ciphers like e.g. Chaocipher it was impossible to solve or determine the algorithm even with thousands of letters of ciphertext?

Q for Ed: after 30 years is it time to start revealing aspects of the encryption algorithm ... if Jim actually wants it solved? (definitely a "Jim question", oh well)