Brother MFC-J491DW Online User's Manual page 478

If your LCD error message was [Repeat Jam B Front], do the following:
a. Make sure you look carefully inside (1) for any scraps of paper.
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b. Squeeze both levers (1), and then open the Jam Clear Cover at the back of the machine.
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c. Slowly pull the jammed paper out of the machine.
d. Close the Jam Clear Cover. Make sure the cover is closed completely.
When finished, continue with the next step.
5. Put the paper tray firmly back in the machine.
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