A common service call is someone getting lines on the copies or when they scan. This is something you can easily fix yourself. When you lift the automatic document feed up out of the way you will see two pieces of glass. A large one for book copying and a long thin piece of glass next to it.
Take the copy with lines and put it on the large piece of glass face up.
Follow the lines with your eyes to the long thin piece of glass on the side. That’s where the hidden dirt is. Clean that with glass cleaner and a paper towel. You may have to rub it well but that often will fix the problem.
If you still have lines after cleaning the slit glass than you need a service call. However, if you get the lines on copies but not prints then it probably is a dirty slit glass so you may want to clean it a second time a little more firmly.