AIO V715W Printer - Color Quit Working

I purchased my V715W printer on 5/27/2011 from Dell and use only print cartridges I order from Dell. Yesterday I was printing a number of documents which included color items. This morning I started finishing my print routines and no color printed out. I thought I was out of ink and put in a new cartridge (color series 24 p/n X769N) but still no color. I decided to print using the "color ink only" function but got blank pages. I put the old cartridge back in and checked the ink supply (it showed 3/4 full). I did a "deep clean" - nothing. I cleaned the top of the printhead. I didn't remove the printhead from the printer because I couldn't figure out how to snap it off the metal rail and I want to break something. At any rate there is still absolutely on color printing capabilities. It is like the color function is DOA.

Is there something else I need to try or is this a warranty concern?

Thanks, retired05