You mathematicians are a strange bunch - don't you ever get bored with logic, calculations, 'proofs'... (or whatever false flag you want your maths to sail under)? I certainly do.
If someone else had offered a timely hint to the endgame, I'd have kept my own offering - and my opinion - to myself. But please don't try to convert me (the missionary zeal in this thread would put a sect of religious fundamentalists to shame).
Believe me, there are others like me who hanker back to a time when Listener puzzles were complex and ideas based - we're just not very well represented online.
Enjoy the love-in amongst yourselves, and please accept my not wanting to be part of it (you'll probably have a few more just like this before the year's out - maybe drop a timely hint in future?).