I think you might win with the first go
Looking at this, I got quite excited when I saw that counting on 8 from G (as in the first G8) give you "N", but it's not a theory that holds true for any of the other letters. Also, although the two Us both seem to be represented by T3, there doesn't seem to be that consistency in the other letters, e.g. N seems to be represented by G8 (twice) and T8
The "Lost" clue means nothing to me! I'm stumped I'm afraid