If it happens on copies the fuser is the issue and you should be able to see the lines on the fuser roller, replace if so, if it is only prints then it is likely the SCSI cable that attaches the RIP to the IOT, try reversing it and rebooting the RIP.
Still hard to tell.
Looks like Magenta and yellow drum or M/Y lasers(dirty) is faulity. Printing a full sheet halftone 25% of each CYMK would narrow it down. You can swap the color drums to help troubleshoot the issue if the problem stays with same color its likely laser or developer. What is the current yield of the drums?
Hope this helps.