Syzzie,
That's strange, I've just checked the file and it's fine before sending to Dropbox and it's fine with the on-screen PDF, but I have just printed a copy, and I also have letters missing in the same words. (fi missing from films and the tt in tha word letters)
Anyone else having this problem, if so, just look at the on-screen PDF and fill in the missing letters on your hard copy.