You are proly correct as the factory TSB on the cooler lines was for isssues at the crimp fittings. If you can find Ron, aka cuisenartvette, he had a line on a place to re-manufacture/rebuild those lines local to him in CA.
Although, it could be that luck is with you and it's just that the connections at the block are loose or one of those senders are leaking?
I would think if you could find a Heavy Equipment repair shop they might have a lead as to making up/ or repairing our lines? I was thinking that someday I would try to make up a set of lines in Aero-quip s/s but the connection at the cooler has me stumped, no threads at that end.
tom