Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Do the black smudges repeat themselves down the page?
(Try photocopying a blank page, in order to see the smudges quite exactly.)
If so, a component in the machine with the circumference around of the distance between the patterns of smudging, or the distance between the marks, has a defect or problem.
If it is the photosensitive 'drum' or developer, such a component cannot be repaired, and most usually will have to be replaced.
(If you can scan an example of the smudges, or an example of the blank photocopy test run I suggested, and send it to me with your Reply, that would be ideal for my estimating just what exactly is wrong. Visual information like print defects on pages are so much better understood from an image than from a verbal description.)