I've got a feeling that my laser printer's drum could be wearing out. I just printed a fully black page as a test, and this is the result:
Note a small degree of horizontal banding as well as overall image "roughness". Is this patterning normal, or is the drum wearing out? Do I need to replace the drum? (I've printed less than 4000 pages on this drum unit.)
Edit: The printer is a Brother HL-2170W. It is nearly three years old and was purchased refurbished; the supplied drum unit has a specified yield of 10,800 pages. The drum was never replaced, and the toner cartridge has 70% of its life remaining. All supplies used in this printer are genuine Brother supplies. I've cleaned the OPC drum itself with minimal improvement, and I've cleaned the corona wire as well. Could the failure be related to the age of the drum unit?
Edit 2: Blank pages are clean and printouts are free of repeating extraneous marks.