Font suddenly changed

Love the plugin Bas! Very classy looking and simple to use.It has been smooth sailing up until now. All of a sudden, the font has changed on the pdf. It looks like an old typewriter font with random spacing. sometimes the letters overlap and others the spacing is very wide.
I read the FAQ and info page on changing the font but have no clue about css or php to try and change the font back. Is there an easier way to change the font back?
Thanks Bas.
All the best,
Ben