Dell 2665 colored vertical streaks

Question

Our Dell 2665 printer is printing colored vertical streaks. If a multi-page document is printed, they are worst on the first page and light to nonexistant on later pages. They appear on every print job:

We have tried the suggestions from the Dell troubleshooting page of replacing low toner cartridges, replacing the transfer belts, and replacing the drum cartridges. We also tried the raster optical scanner window cleaning suggested on another Dell support page. No effect from any of this.

Google turns up other users with this same issue (1, 2) but no solutions.

How can we fix the printer to stop these streaks on every print job?

Answer 1

A helpful Dell chat employee pointed me in the right direction: the maintenance kit for this printer completely eliminated the streaks and also the sporadic faded colors.

The kit is part 7XDTM, sku 331-8956, and includes "Belt Unit, 2nd BTR and CST Retard Roller".