Epub to PDF conversion-characters scrambled

[tonkins]

I'm a newbie to Calibre and am using it to convert Epub files to PDF. Most work fine but one file is causing a problem.
Certain lines(~2%) have the characters scrambled, jumbled up
and overwritten by each other

The original Epub file is fine. Fiddling with various settings in the convert options does nothing, except for 'Disable Font size rescaling' which changes some of the scrambling
from with Normal font size rescaling

to with Font size rescaling disabled.

Selecting the scrambled bits and copying them into word gives me jumbled garbage and some of what should be there written backwards with the spaces between words wrong..eg

the pile. Donald had emer*ged from his office and was advancing across the yard in our direction. His sudden appearance had a marked effect on Tam and Richie, whose faces showed that they were concentrating hard on their work. Tam leaned over the side of the truck and pulled out the post hammer.
‘Glad

becomes

the pile. Dosawn dnaa ledc ihf faor dmese ihm orf deg
gnicnavda in our direction. His sudd eyenh t ataphtp deewohasr saencacf ees ohwh ,aedih caiR dnmam aTa nor ktceedf fe were
concent.rarmmaethi ntgsop h ehatr dt uoo dne ltlhupe dinra wkcuorrtk e.h tT afom ed liesa ehnte dre vo
‘Glad

Any suggestions as to what is causing this problem and how to fix it please?

[jjabrams]

Try opening the book in html. Find the problem sections and see if anything looks odd. There are a lot of different problems that can occur that won't be visible from the epub.

Alternatively you could try uploading the epub in mobi creator and see if the problem carries over to the .prc format.

"The quieter you become, the more you can hear."