If the paper feed roller is stained, the printer may not feed paper, the paper jam alarm will on.  In that case, clean the paper feed roller
as follows:

1. Turn off the power switch and unplug the printer.

2. Unplug the power cord and interface cable from the printer.

3. Open the upper cover and remove the laser toner cartridge.

4. Wipe the rubber part of the roller with a soft damp cloth. After that, wipe it with a dry cloth to remove the moisture.

5. Reinstall the laser toner cartridge into to the printer make sure the cartridge is fully inserted and close the upper cover.  

6. Put the paper on the paper tray.

7. Make sure that you have turned off the power switch, and then connect the power cord and interface
cable to the printer.

8. Plug in the power cord and turn on the power switch of the printer.