I haven't read any post that looked like it might include a clue. I'd first like to try to solve the puzzle with no help. But I'm not a puzzle person, and if it's not a letter substitution problem then I don't know what type of puzzle it is. If anyone should be able to figure out the type of puzzle it is then so be it, I'll figure out what I can, but if it helps to be familiar with various types of puzzles then I don't have that familiarity and am at a disadvantage.
--Percy