I have E310 which I've used since 8.6 B&W G3 so - what port are you hanging it off of? Which usb card? and macs w/o built-in usb can have trouble I read on lexmark site? I have xlr8 pci usb dual port which has 11Mb/s on each port, and provides more power as well which is handy - even though I hve 2 built in ports on my system.
Try 1/12/01 DDK USB 1.4.7f2 and look for 1.4.8 but 1.4.1 should work. I never needed to add anything but the PPD for Lexmark printer description. I won't ask if the printer is turned on when you run the utility and usb cable is connected.... but are they? Try another cable?
Gregory