An indication that your printer needs a service is a buildup of toner and paper dust in the paper input tray. These trays are usually plastic and can be cleaned by washing with detergent or wiping with methylated spirits. If toner reappears soon after the tray has been cleaned, you may have (or have had) a leaking toner cartridge in the printer. Leaking toner is spread throughout the printer and often ends up in the paper tray at the bottom of the printer.
If you have a leaking toner cartridge, stop using it immediately and service the printer to remove excess toner before it leads to expensive repairs. When toner is spread through the printer is can damage rollers and the fuser. When toner melts onto the thermistor in the fuser it prevents the thermistor from correcting the fuser’s temperature. In this case the fuser will over heat and damage its components which will then disintergrage, this will cause paper jams at the rear of the printer.