Dell 5100cn

the dell 5100 toner cartridges sit in the top of the printer as you already know, but by simply changing the cartridge, the problem will not go away. the toner is actually fed down to the developer unit by a feed tube. the tube itself holds about 20-25 grams of toner in it, enough to print a hundred to two hundred or so pages. the best solution is to by a quality toner cartridge, and cycle it through the printer. if that doesn't fix your problem than you more than likely have a more serious developer or imaging drum problem. i would recommend www.libertytoner.com, they were the first to release an after market product for this printer years ago and the toner works great.