Printer prints grey instead of black.

I have a lexmark printer and a macbook. Unfortunately I can't find the CD that came with the printer. The cartridge has been replaced, and the problem is only with the macbook, not the desktop (not Apple) using all the same settings. I understand this is a common problem but haven't found a solution. If you can help it would be greatly appreciated, even if it's a temporary solution. Many thanks. G