Not printing out the back (in large format)

you may have to make another tray the default tray
then you select the paper size to print on and put the size paper in the default tray

The light means that the printer is out of media, or the media did not feed properly

What you can do

-Load media into tray and press Continue button to resume printing.

-Check that the media is loaded correctly in tray

-Press Cancel button to cancel the print job.

You probably printed a document that was forced to the manual feed. Place some paper there and it should print. Go to your printer preferences and set the default tray to tray1 instead of Auto.

YOur problem is likely worn feed rubber. It is an old machine. Has it ever been serviced?
Did this happen after a paper jam?
Try this: UNPLUG the copier Take out the paper tray. Prepare a dry cloth that is dampened with WD 40. Open the door on the right side of the coper. You should see 1 large, gray or black rubber roller. Gently wipe the roller with the WD 40 cloth, slowly turning the roller. It only turns 1 way, towards the exit direction of the paper from the copier.

Let the WD 40 soak in, about 10 minutes. Put the paper tray back in, plug the copier back in and try to make a copy. If it makes a copy, the feed roller needs replaced, If it doesn't make a copy, check the top sheet of paper in the tray. If you see skid marks, you definitely need a feed roller. No, they are not easy to change.

As long as the roller feeds, go for it. When it starts slipping then you'll have to do something about that feed roller.

Paper light flashing could mean several things on this machine.

There could be a paper jam in the machine. Open the front cover remove the drum and toner and look in the machine. You can also check in between the drum and toner by removing the toner from the drum. Open the back cover and look for a Jam as well.

Try putting a piece of paper in the manual feed tray which is right above the paper tray, sometimes on certain documents the margins are too big and asks to go into the manual feed slot.

You need to try a thicker paper, Heavier stock to double print the page. Slightly more expensive. Recycled paper typically will not work for this type of function. I had this same problem and found this was the only solution.

You need to clean the feed roller, if you take out the paper tray and tip the printer on it's back you can see the roller and clean with just a damp cloth and try printing again...

Check if the software you are printing from is set to feed from the manual feed (top back) instead of the main paper tray. You can put a sheet of paper in at the top to see if it takes that instead of the main tray, If so, change the settings in the Printer properties to feed from the main tray first.

Hi there
I've had a similar problem in windows instead of the mac, but it sounds like it's a 
similar problem where the computer's telling the printer to use a 
different sized paper to what the printer's been told is in the trays. For example, if, say, your document is set up for A4 sized paper, but the printer is set up to think it has Letter sized paper in the trays, it'll ask to have A4 sized paper installed in the tray instead.
 

Go into the system setup on the printer and select the paper setup menu.  

Select Tray 1 and choose the right paper type and size from the settings (After you choose the paper type you have to go all the way back through the menus on the printer and choose the paper size as well)

Hope this helps! 

Is this a top feed - that is paper loaded on top at the back bottom feed from a tray underneath? Top feed take one sheet of paper and gently push it down whilst the printer is trying to grab it. Tray feed - take tray out make sure no paper fragments are in the tracks and find a nail board and gently abrade the pick up rollers.