Huh, the same thing just started happening to my Dell Photo 926 printer today. But it worked fine for, gosh...5 years before this? I keep hoping to see some answer suggesting a solution, since it's clearly a mechanical issue, but no luck so far.
You may try the following steps.
If the above steps do not resolve the issue, the printer might have to replaced. Please refer to the manual for more information http://bit.ly/13xGjyC.
Please reply if you have any questions.