It is interesting that we can put the original toner cartridge back in the printer and everything prints ok except for the "burn" marks on the right side.
It only prints the black early with the latest two toner cartridges. My real question is how can toner cartirdges behave differently. Two of them print the black ink early and one of them leaves the burn marks.
Do I try a fourth black toner cartridge? Are there warranties on toner cartridges?
Thanks for the suggestion.