A user has reported that their office printer has developed a recurring problem. Whenever they print documents, there are noticeable lines down the middle of the printed pages. The printer is a relatively new laser model, and the user has already checked for paper jams and found none. As a technician, what is the most likely cause of this issue that you should first investigate?
Clean the printer's corona wire.
Replace the imaging drum.
Calibrate the printer.
Use a different type of paper.