You might look at this thread (https://bitcointalk.org/index.php?topic=50519.0), especially post #5.
I was sure I couldn't do it, but I did. I stopped thinking so hard then I casually put a guess it and it worked. Stupidly I had no motor memory of this password. I typed it a few times months ago and only said it in my head since. I assumed some sort of horrific telephone game effect in my brain had ruined it.
Thanks all.