I have an old Lexmark x502n Laser Multifunction color printer.
It works perfectly, except it stripes everything I print with white lines:

I searched on internet and it seems that whenever something like this happens it means that you have to clean toners (their contacts) and sometimes you have to clean rollers. I did search in the printer utilities software and unfortunately there is no option to do it automatically.
Is that right? If not, what should I do, and how should I do it?