I have a Laser jet P3015 and something has happened and it has stopped duplexing. It has been working, duplex is checked in the settings and on the computer. I am using a mac running OS 10.7.1

Do you have the 1320D or just a 1320. Only the D version will duplex automatically. The base version requires you to manually duplex. If you are sure you have the duplex version, then check the settings in the print driver and make sure it shows that the duplex option is installed. The driver often defaults to no duplexer.

In Windows 7, you can right click on the printer under Devices and Printers, then select "Printer properties" (not "Properties"), then under "Device Settings" you can set the "Duplex Unit" to "Installed". Afterwards, you can go back to "Printing Preferences"->"Finishing"->"Print on Both Sides"->Print on Long/Short Edge.

Make sure that in both the printer preferences no multiplexing is set up and that no multiplexing is set up in the the printing preferences of the software you are printing from

You have to print the first side then take those prints and put them back into the paper tray to print the second side (Manual Duplex). If this were a DN model it would have built in automatic duplexing and you cound select "duplex printing" from your print setup screen and the printer would print both sides automatically.

chek inside printer for pieces of paper or something...try to clear paper feeders...Good luck

There must be some problem in your settings. Check it out properly

HI ayyasamyr:
This your problem.
13.10 PAPER JAM The event log message for a paper-delay jam in the duplexer is 13.10.
1. Check the duplexer and the rear area of the printer for obstructions or damage.
2. Check PS1701 and PS1703 in the duplexer for correct operation. Replace the
duplexer if a sensor is defective.

Hope this helps

check the driver

does not print from bypass tray (manual feed)
does not print on thick paper (check paper type)

Duplex on this printer is manual, that means that you will have to re-insert the paper by yourself.

This if you have the 2420n, the 2420dn instead is the duplex model.

Here specifications, look where it says duplex, 2420n had only manual duplex (the printer wait for you to re-insert page).

Check for new drivers(for your printer) or upgrade, for windows vista....Sometime the driver for windows xp is not the same.