Problem printing with Epson DX3800 with iMac G5 on OS X 10.4

I've recently inherited a barely used Epson Stylus DX3800 from my late father. I connected it up and although it isn't listed in the printer set-up utility, I selected a similar model and can print in black & white ok.

However, when I try to print in colour it's as if the heads are misaligned and you get cyan, yellow and magenta all separated. I've tried the various diagnostic functions within the printer to no avail. I've since connected a Windows laptop and (using the Epson drivers) printed a page perfectly.

Alas Epson don't seem to make any drivers for Mac so does anyone know any way in which I can get this to work properly?

Many thanks in advance.