I have a Laserwriter 16/600 that's starting to show little flecks of toner along the edges of the paper. Nothing large, it just makes the edge of the paper look a little dirty. I got a brand new Apple  brand Toner Cartridge/ sealed/ from ebay and put it in thinking that would correct the problem, that the old cartridge was getting worn out/dirty etc. Well the "new" one has more smudges on the paper than the old one did. The new one smudges in a pattern making the faint impression that a tank ran over the whole paper along with what I intended to print on it. I went back to the original and will put up with dirty edges rather than a page-wide repeated, faint pattern. Even new and sealed, do these cartridges get outdated?  The little green roller in the cartridge has the pattern (in toner) on it that prints on the paper. Why will one toner cartridge produce a nice clean copy and the next produce a dirty or in my case and even dirtier one?  I've done the cleaning inside the printer with the supplied little brush as the owner's manual suggested, but I don't know what that's supposed to accomplish. HELP!