Digital BW, The Print

Hello,
I have seen many people here using Epson 2400, maybe you can help me. I 
have a problem when printing with frontal manual thick paper feeding, 
when I configure PS to print in this config, the preview white board is 
smaller than usual even if my paper is configured as DIN A4. The 
printed image doesn't cover all A4 surface and it is not centered on 
paper sheet, it is somewhat displaced in an asymmetrical layout, with 
two margins about  2 cm and the other two about 4 cm. What is more, it 
seems ink is spreading in one side out of the image border into the 
white margin.
When I print again using automatic feed, the layout on PS and printed 
paper is normal.

Any advice?

Thanks a lot,
Juan Riera