I have an old HP LaserJet 4 which I haven't used in months. Now when I try to print, the quality is blurry and faint. I removed the toner cartridge and shook it up since I thought that the toner may have settled, but it didn't help. When I opened the cartridge compartment again, there was black soot inside the compartment. The I examined the roller (see photo). That didn't look normal. I've seen other printer rollers that were perfectly clean. Is it normal for the soot to be on the roller like that? Is it a problem in the cartridge itself, or in the printer? Anything I can do about the cartridge , if that is the problem outside of having to buy another one? They are about $150 a pop, if one can even be found being early 1990s equipment, and the one I have hasn't been used very much, just infrequently.