Aperture printed image offset by 1/4" on Epson 7800 printer

I'm using Aperture 3.2.4 with System 10.7.4, and Epson 7800 printer, iMac. Have printed many images, working properly. But recently, every printed image is offset 1/4" up. It looks correctly centered in the printer setup screen, but when printed, the bottom margin is 1/4" larger and the top one 1/4" smaller. For this printer, the bottom margin is supposed to be fixed at 0.56" (9/16"), and it always used to be, and that's what the setup screen still says it is. But now the printed image's bottom margin is 0.81" (13/16"), even though the setup calls for .56".

I've tried to compensate by adding 1/4" to the top margin, and that does bring the printed top margin up from 5/16" to 9/16", but the bottom margin remains 13/16"

Anyone have any ideas?