Make sure the paper in the paper tray is loaded flush to the front of the tray.
It's a good idea to remove the stack of paper and re-stack it to get it aligned together, then place it back into the tray aligned to the front of the tray.
To adjust the paper slider... [See the pic below]
Pressing the tabs together will let you move the slider forward or back. Adjust it to hold the paper to the front.
