in reply to commented out s/// prevents script running!
Have you tried turning on warnings and rerunning it - you don't give any diagnostic messages, which would make your life considerably easier. It might well be worth use strict; ing too, given the size of the script.
My guess is that you've incorrectly escaped/matched a quote somewhere and blown though some lines...
"Stercus! Dixit Pooh. Eeyore, missilis lux navigii heffalumporum iaculas. Piglet, mecum ad cellae migratae secundae concurras."
PS - You also may wish to consider using transobliteration instead of substitution as it is quicker.