I have a Dell A940 with serious ink issues. I just replaced the cartridges and now the black won't print. The color is printing just find. I've cleaned the cartridges and made sure they're in the right slots, but the black just will not print. I can tell that something's clogged, but don't know what. Any advice or help?? I'm in Grand Rapids, MI, and might need to get it repaired—does anyone know a place where I could get the printer serviced?