If it isn't a paper jam, it might be that the feed rollers are polished. You can clean them with Tape Head Cleaner (IPA) but the easy way is to hold a pan scourer against them while they are turning. Early Deskjets had this problem and HP would supply a fix kit FOC which was a beautifully engineered assembly with three Scotchbrite pads and a floppy disk program to turn the rollers for 20 minutes......
Bill
March 2007