The only thing I can think of based on the inforamtion you provided is that the pickup roller is probably worn based on the age of the product. I have a couple of things you can try that may help you. But before I cover those...let me be clear on a couple of important points...
- I am an HP employee but I do not speak for or represent the company in this forum
- Try these at your own risk. While they may work, they may also damage your printer
Try cleaning the pickup roller and seperation pad located in the front area of the printer. To do this....
- Unplug the printer from the power source
- Remove the paper tray
- Open the top cover and front covers
- You should be able to reach the pickup roller (upper and lower) and seperation pad with a cotton swap dampened with isopropal alcohol from the top and bottom via the open doors and paper tray area
Sometimes, scuffing the lower pickup roller with any emory board will also help. Warning, over time this will damage the rollers/pad so do not repeat it too often. This of this as a last effort before replacing this product.
I hope this is useful and besk of luck to you...