Hi there bogdanw and pgolik, thanks so much for your replies.
bogdanw, I have installed the driver v12.62, however it still defaults to idle and fails to print, unfortunately.
I also tried to install the firmware update, however it gave me a message that it was not possible to do (my printer wasn't compatible with the firmware upgrade - not because it wasn't the right firmware, but something to do with the printer itself).
Anyway, I have removed the printer and cleared the print settings prior to re-adding the printer, restarted both the printer and Mac, and I still can't make the printer print, even with the new driver software (please see attached screenshot):
...I have a feeling it has something to do with the network (I have it plugged via ethernet cable into my modem/router, so it is available on the home network for all devices to print to), and I just can't figure out how to fix that - like I was able to fix it in my old Mac with the old 'preferences' system)..