Vertical streaking is a common complaint among owners of Lexmark C500 series color laser printers. This can be caused by a buildup of toner deposits inside the toner cartridges. It is possible to service these cartridges to wring some more life out of them.
First, prepare your work area. I put the cart down on a few paper towels, as you will be spilling a little toner. I also have 91% alcohol, some cotton swabs, and a small phillips head screwdriver.
Step 1: Remove the baffle
Hold the cartridge with the roller side up. You should be able to see where the streaks in the toner on the roller. The layer of toner should be as even and solid as possible.
First take the 5 inside screws off of the baffle. Be careful not to touch or scratch the roller. These screws are short. They hold the blade assembly to the underside of the carriage. Don't apply too much pressure to these screws.
Step 2: Remove baffle and carriage
Remove the two outer screws. These screws hold the carriage to the cartridge shell. They are about an inch long.
Step 3: Take off the baffle
You can now remove the baffle. Be careful not to bend it or scratch the roller.
Step 4: Remove the carriage
The carriage can now be rotated upward from its seat in order to slide the roller out of the cartridge. There is a layer of foam that helps to seat the carriage onto the cartridge. Work it loose gently.
Step 5: Remove the carriage cont'd
With the carriage rotated vertically, you can lift the assembly off of the cartridge. Set the assembly down with the carriage on the work surface. Keep the roller from touching anything.
Step 6: Remove the blade
Under the carriage is a pair of plastic blades which feed the toner onto the roller and collect waste toner. The roller turns toward you, so the top blade is the one which causes the toner to be streaked. Grabbing the corners of the blade assembly, you can gently work it loose from its seat on the cartridge. There will be a lot of toner, so try to keep it from flying around too much.