I have a Lexmark Z33 so I tried the Z35 driver and everything worked fine until the last instruction:

$ /usr/lib/cups/backend/z35
direct z35:/dev/usb/lp0 "Lexmark Inkjet color printer" "Lexmark Printer"

$ /usr/lib/cups/backend/z35 utilities
ERROR: Unable to open printer port "/usr/lib/cups/backend/z35": Text file busy

How can I fix that? Any suggestions?