About a week ago I started getting ink supply low on two of my ink cartridges. Next came the out of ink on one and printing came to a halt. I went to the front panel, selected change ink, took out the empty cartridge, shook the hell out of it. I put it back in and it printed 12 24 X 36 prints. Then the second ran out. Did the same thing. Printed 8 more. All of the prints looked very good. Then I had one of the two run out. Shook it but nothing. I have a big box of supposedly empty cartridges hoping some day I could get a discount turning them in but none of my local office supply stores carry the big Z3100 cartridges. I took one out of the box of discards, shook it, put it in, voile´printing again. I don't recommend this as a way to operate out of a box of empties but, if you ever get the out message, remove, shake, keep your fingers crossed, put it back in and maybe you'll have the same experience I did.
With this economy I don't always have an extra full cartridge lying around. It takes at least a day to get one shipped.
Jack