I have an Epson 740i printer. For the last four years I have had aggravating experiences when trying to replace the ink cartridge. The printer supposedly figures out when the cartridges are out of ink, but this almost never works. Then this happens, as mentioned on an excellent support page I found:

Ok, I'm trying to replace the cartridges, but when I hold down the ink button (first on the left), the print carriage just goes back and forth a few times but never stops for me to replace the cartridges. -- Epson 740 ONLY

There is a trick to replacing an ink cartridge if the printer doesn't believe the cartridge is empty. Normally (this part is documented under your printer cover), to replace a cartridge, you would hold down the ink button for 3 seconds causing the carriage assembly would come to the left allowing for cartridge removal. IF the printer doesn't believe the cartridges to be empty, then all that will happen is the carriage assembly will move right and left and not stop for you in the open area. THE TRICK (and this ISN'T under the printer cover) is to hold down the paper feed button (center button) for 3 seconds. This will bring the print carriage to the open section and allow you to replace the cartridges regardless of whether the printer thinks it's time to change the cartridges or not.

From http://www.sbcsc.k12.in.us/techsupport/printers/EPSON_FAQ.html

10:14:53 PM