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Read this before Posting PDF Questions and
How to ask a question about conversion problems
Did you try reconverting a previously converted book - copy existing PDF before you reconvert, just in case it goes awry. If its OK you'll have to compare the settings it uses, with the problematic conversion. If it's not OK then you can put the copy back into the library.
BTW if you open your Kindle Book in calibre ebook-viewer you can try creating a printable PDF from there - Ctrl+P to Print.
BR