IMO, "breaking in" a Brooks is sort of a myth. Yes, they do change over time, but if you can't set it up in a way that you are comfortable right away, it will probably never be comfortable. They are best when they are hard and new. You may need to spend a bit of time making very small adjustments, but once you get it right, they're the best.
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1964 JRJ (Bob Jackson), 1973 Wes Mason, 1974 Raleigh Gran Sport, 1986 Schwinn High Sierra, 2000ish Colian (Colin Laing), 2011 Dick Chafe, 2013 Velo Orange Pass Hunter