Dell 2350d/dn Mono Laser Printer - Manual (Page 129)

3.
234 Paper Jam - Check Duplex
There is a paper jam in the duplex unit, but the printer cannot identify the location.
Remove Tray 1, and then depress the lever in the duplex paper path area..
CAUTION: The inside of the printer might be hot. To reduce the risk of injury from a hot
component, allow the surface to cool before touching it.
1.
Remove any jammed paper. 2.
Replace Tray 1. 3.