Separate colour cartridges in a carousel IIRC on these, and the most common reason for streking is a worn scraper blade on the drum. What colour are the streaks, I am going to guess they are black, and nothing on the other colours. Another is if there is toner spilt onto the paper path and the fuser, and this is being picked up. You should try printing a few pages of each colour using about a 50% fill, and see if that picks up the loose toner.
We had an older relative of that copier, and the consumables were pretty expensive, though they were cheaper than the Tek Phasor wax blocks. Those were $100 for 3, and the maintenance tray was $200 for a tray that did 1500 prints, though I was able to do a mod that got easily 6000 plus prints out of them without any issues. The printer would use 1 block of each colour on startup or over a week irrespective of the number of prints.