3000cn Printer Printing thick black vertical Lines!

Model: Dell 3000cn Printer

We have had this printer for atleast a couple of years now, but only recently it has developed this problem with printing all types of media colour or in just black & white. We have cleaned the inside and used the brush on the side several times and have currently printed around 50+ pages through to see if it would clean itself. also have tried a new cartridge with no difference at all. We took the drum out and can see on the roller these marks on the blue roller as well as the ribbon? cleaned them both but when printing again it comes out clearer but then get to this stage after 3-4 prints.

Has anyone had this problem before and know the solution? Or is the printer dead so to speak?

I have done various searched on here that have similar problems but either not in the middle or they were having horizontal not vertical lines. So not sure fi this applies to us or not.

I've attached a photo of the paper printout for anyone who can help us fix this issue?

Note: we have not replaced the drum since new. And do not want to buy a new drum if it won't guarantee a certain fix as we are considering buying the 2130 model.