When a printer works but the page looks wrong, the hardware is usually fine — the ink or toner delivery is the problem. Inkjet printers spray tiny drops through microscopic nozzles, and any nozzle that dries out leaves a gap that shows as a streak or band across the page.
Laser printers work differently. They bond toner powder with heat, so poor output usually means a low or unevenly distributed toner cartridge, or a drum that has worn past its life. The fix is replacing or redistributing the toner, not cleaning heads.
Colours go missing for the same reason. If one cartridge is empty or its nozzle is blocked, that colour simply drops out, turning a colour photo into a strange tinted version of itself.