If you have run out of ink on your Hp Envy 5660 printer and the print heads are dry, you can manually clean them by using a Q-tip dipped in isopropyl alcohol to gently wipe away any dried ink that may be present on the printhead. However, this is not done regularly enough and could end up damaging your print head by causing wear or even causing it to fail completely. This can cause problems when it comes to prints being made as well as poor quality copies on poor quality paper.