Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
You have to get to the rear rollers etc., through the interior or 'cartridge area'. See these illustrations, for the steps:
Remove paper if needed, with both hands and pulling slowly.
Locate the paper path cover inside the printer where the blue arrow points to it:
Pinch the two tabs together and open that cover:
then pull it upward. Remove paper from rear feed area as needed, reverse steps to close printer.
Then open the duplexer cover:
and remove any paper gently and carefully.
Then push duplexer cover down until you hear it click into place.
Then push down the paper cover until you hear it click into place. (Push down at left and right edges, not in center.)
Also you could turn the printer carefully onto its right side:
and remove any paper from the bottom slot more or less.
But there is no rear cover. The duplexer is accessed from inside the printer, unusually.
If this answers your question adequately, please rate my answer, so that this case may be closed. Thanks. (Ask for further details if you need them.)