Paper feed issues are frequently caused by dirty or worn out paper feed rollers. If you can see the paper feed roller in the paper tray, clean it with a cloth which is lightly dampened with a spray soap such as formula 409. Just about any household spray cleaner will work. Those with bleach, or alcohol should not be used. Do not spray directly into the printer. Dampen a cloth or a lint free paper towel and clean the roller. You may need needle-nosed pliers or something similar to fit the cloth into the paper tray. I know that my hands are not small enough to fit into there.
If this does not work, you can weigh your options of taking it to a shop which services Lexmark printers (Dell printers are made by Lexmark). They may be able to replace the roller for you. Consider the relative cost of repair vs replacement.