This will solve your problems. Most other problems concerning received document quality can be solved by replacing the cartridge. Printer's are the simplest of all. I would first recommend using a can of high pressure air to blow out the interior of the printer. After that, take the inkjet cartridge out of the machine and gently clean the bottom, where the ink comes out, with, you guessed it, isopropyl alcohol on a soft cloth.
Laser printers are a bit different.
They also have a fuser unit so you can apply the same procedures as mentioned above for copiers with edge to edge lines or moving spots. A final point. Always follow use of isopropyl alcohol on any glass surface with glass cleaner. This will remove any streaks left behind by the alcohol. Call a tech, or . . .