Finding a clue that will help us analyze K4.
Step 6: Remove everything between 'GRAY' and 'DARK'
Here is the 'reversed letters' technique that Sanborn also used in Part 1.
Step 8: The clue for use with K4
As mentioned in part 4, this was going to be convuluted and complex.
The result is correct as you'll see when we use it with K4.
Step 9: Next: Finding the doorway.
The rules for solving Kryptos are listed in Part 1. Have to get into Sanborn's mind to make any progress.
The 'YAR' clue for solving K3 is very clever and very simple.
Part 1 of the final solution can be found in Part 10 of this series.