If the file does the problem and you can't use PitStop (strange situation) do the following:
1. open a pdf file in Photoshop, then rasterized 1200 dpi in Grayscale mode.
1200 dpi more then enough for quality 1-color print.
2. use curves Ctrl-M or Levels tools for correction black color to 100%
3. If you have several pages in pdf split them to 1-pages files.
4. Make Action in Photoshop.
5. You have several grayscale bitmaps with 1200 dpi.
6. Place bitmaps for example in Indesign and save file. If this periodical next time will change only links.
7. Now you can make pdf for print, but not use jpg or zip compression, choose "Downsaple OFF" in pdf setting.