Get some nail polish remover, the cheapest type that contains acetone. Avoid any "moisturising", "nourishing" or other heavily modified ones. If you have acetone, you can mix it 1:1 with alcohol (isopropyl/IPA ideally).
Now pull out the paper tray and look under the printer. You will see a large rubber roller, usually grey, that picks up the paper and slides it out of the tray. Using a soft, lint-free cloth or paper towel dampened with few drops of the liquid described above, wipe this roller several times, trying to turn it around (with the printer turned off) so that you wipe the whole roller surface. If you cannot move the roller, run the printer once or twice and clean the roller again - it should stop in a different position each time. Acetone evaporates quickly, so add a drop or two between wipes.
Also make sure to clean the separator - it's a rectangular piece of rubber on the paper tray - it has to have enough friction to keep the printer from taking up 2 or more sheets at once.
Be cautious not to spill acetone on your printer or any plastic objects - it will leave unsightly marks, as it dissolves most plastics.
Good luck :) Abd come back with a testimonial if helped :)