Fixing errors in PDF conversions

I have converted a couple of PDF scores into MuseScore format, and for the most part it worked quite well. I've attached a file with some small problems. The problem is extra rests inserted here and there (e.g., bar 2, bars 27 and 29), probably to make up for the mis-read of another note. These rests are in grey. I can't seem to get rid of them or fix the mistranslated notes. (I would upload the files but don't seem to be able to for either PDF or .mscz files (on Mac, in Safari)