How can I fix my HP Photosmart 7450 printer from jamming?

My HP Photosmart 7450 printer has been continually having paper jams. When it starts up after doing the head cleaning bit it goes straight into getting some paper which then jams. I did initially remove it from the front (I NOW know thats a big NO-NO!) but even so, is there a way to fix the problem? I have tried to uninstall and reinstall it but no resolution of the problem. I have changed the ink cartridges. I think the problem is mechanical but don't know how to get into the printer and even if I can open it up what to "fix". Can anyone help me?