Duplicate post by Byronk
Once all the ground work has been done where there are multiple options for all but a few starter clues, it's hard to give up. Having given up twice, I went back again and after narrowing down the options to three possible solutions, the third one proved to be the correct one. I find the argument about a thin line of logic throughout not to be the case, except in retrospect. One of the four variables cannot be narrowed down by logic until towards the end when it drops out through sheer trial and error. Overall I found this one tough because there is absolutely no redundancy in the clues, so it does require a lot of slog. Solving the last clue however was a joy!