Gutenprint - Please see Gimp-Print

Hello,

I'm having difficulties getting a borderless photo printed on 4x6 photo paper from my RX680. What's worse is the there are borders on the top, left, and bottom edges, but none on the right.

Here's my set up:
Macbook Pro (last generation) with Mac OSX 10.5.6
Gutenprint 5.2.3
Epson RX680
Printing from iPhoto

I've set iPhoto to print borderless in the print dialog boxes. No matter what I do with other settings in the print dialog, I cannot get borderless, nor can I get the borders to be even. It's almost like the printer is printing on the wrong size paper; but I'm absolutely sure I'm setting everything in iPhoto to print on 4x6.

Help! I've gone through my first box of photo paper, and I have no result that is good.

Thanks,
vf-x