they pull me back in.

I found some Morse code cipher systems.  This was an effort to try one of them:

Pollux Cipher

Sometimes there are ciphers that seem to fit all of the conditions needed for K4 and the method is so tantalizingly interesting that you can’t but hope it works.

This one didn’t but it’s entirely possible that it was operator error.  For anyone who likes Morse code work, these may be of interest for you to read up on.