I don't believe it, but I have now completed this! The instruction was hard to follow at times due to being unable to source a clearly legible copy of what was required. However, once I discounted the letter in the start cell, it seemed pretty obvious from the first 4 letters what the message was going to be and, hey presto, that hunch worked. The end game certainly tested me to my limits. How people can construct puzzles like this is beyond my comprehension. Truly remarkable.