|Here's what I've tried...|
1. Cleaned corona wires carefully several times.
2. Live in Denver, CO...low humidity.
Update: I had a spare drum and replaced problem drum with it. STILL getting the bad print... COULD THIS MEAN THAT SOMETHING ELSE is wrong with printer, e.g., curcuit boards, other stuff?
[The spare drum came from an HL-2040 that some plastic guides for the paper take-up broke on. Print quality was fine up until time I salvaged the drum/toner cartridge and discarded the rest.]