This cartridge produced vertical dropouts/fadeouts immediately upon installation. I changed back to my old cartridge and the problem went away. So it's definitely the cartridge and not the drum or other printer component.
This isn't an isolated case. See also the recent (July 27, 2016) review by J. Varner, who reports fadeouts with a brand-new cartridge.
Unfortunately I had bought this cartridge to have on hand when the need arose, so by now the return period is past. DO NOT buy this cartridge until right when you need it, in case you get a dud and have to return. When they work, they work great. But be aware that you're taking a chance with this product and be sure you can return within the allowed time.
You have to expect some duds if you take a gamble on recycled cartridges. But poor quality control is unacceptable when paying top dollar for the genuine item.