Hi, I'm Pete. Welcome to JustAnswer! I'm reviewing your question now, and will post back with your reply ASAP.
Approximately how old is the printer?
Can you attach a scanned image of a page showing the greenish vertical line?
Hi Richard, thanks for the images.
These lines are caused by a defect in either the color cartridges or the drum roller within the cartridge, or possibly a faulty drum unit.
The defect could be anything from a physical dent in the roller to wear and tear that is preventing even distribution of the toner powder.
If replacing all of the cartridges doe snot help then the problem is likely with the drum unit.
Hi, just checking in on your question, do you need any further assistance?