Thanks for reply.
Sorry for not being clearer but I have installed both apple and lexmark packages and when I hit the + on the printer preferences pane the Add Printer window pops up. For the printer mentioned the fields are autopopulaeted with what appears to be the correct info. It is here, when I press the Add button that software update is initiated. It tries to find what I presumably have just downloaded and installed. Eventually it quits with an error that the software I am looking for is not available at the moment. I can get the printer working by using the 'Generic Postscript Printer' in the 'Print Using' drop down men, but would prefer to use the native lexmark driver.