When paper is not fed from the paper cassette correctly, clean the roller inside.
Turn off the printer by pressing the 
button.
Unplug the power cord, and then disconnect the power cord.
Disconnect any cables if they are connected.
Slide out paper cassette.
Stand the printer with the control panel's button at the top.
Be careful not to trap your hand or fingers when standing the printer. Otherwise you may be injured.
Do not leave the printer standing for a long time.
Dampen a cloth with water, wring it out thoroughly, and then wipe the roller while rotating it with the cloth.
Return the printer to its normal position, and then insert the paper cassette.
Connect the power cord.