I changed the black and all 3 color cartridges and now it leaves wide streaks of color. How can this be corrected?

There is a good chance that your color ink cartridge needs replacement. You can tray wetting a paper towel and putting in the microwave for 5 to 10 seconds then placing the cartridge on it for a few minutes. This sometimes will correct that type of problem...Be careful the paper towel will be hot (handle with care).

THE PAPER SELECT ARE NOT COMPATABLE, SELECT LGL IS EQUAL TO 8.5/14 FLSC IS EQUAL TO 8.5 /13. TRY TO SELECT BLACK COLOR OR CLEAN YOUR DEVELOPING UNIT.

You can try changing the print density under print quality in the control panel. YOu can also check the reset to factory default and see if this helps. It could need what is called a maintenance kit where the fuser and rollers are replaced. I install these all the time and sounds like this is what you need.

when you open the front of the print you will see the streaks on the black transfer sheet.

Close the front door half way or until all the cartridge doors open.
You will see the same streaks on the problem cartridge(s) as on the transfer sheet.

Change that particular cartridge, let the printer recalibrate, and presto streaks are gone.

Out of one or more toners. If you have removed and replaced a cartridge in error the % remaining is reset to 100%. Try to determine which color is missing in your print out (usually black), and then follow menu instructions to replace that cartridge. The ends are color coded so be sure you change the correct one. This will insure the remaining cartridges % remaining is correct.

Print in grayscale (black area streaking only) If the streaks are in a black area of a black and white printout, change to grayscale printing.
NOTE: This step does not apply to color printouts.

1. In the application you are printing from, click File , and then click Print .
2. Make sure the printer is selected and click Properties .
3. Click the Color tab, and select Print Grayscale and High Quality .

What I would do is remove all cartridges, wipe the belt w/clean cloth use an air can to clean the machine, check the drum on each cartridge see if there is something, it could be there was a change in Voltage and it burnt the drums. change 1 more toner cartridge to see if that color goes away, if it does then you will know if the drums are the problems.
I've had a problem w gen toners doing the exact same thing, so I had to OEM and it went away. Good luck>

Make sure ur using the correct cartridge.....
for X2580 the cart number is 2 and 3

1.Cleaning the copper contacts on the carts as well as the copper contacts inside the cartridge carrier......

2. Remove the carts....and install the carts thru the solution center...(Start-programs-lexmark-solution center-maintenence -install carts
.......

Clean the ink nozzel using a wet paper towel.....do not whip it ..just press and hold the nozzel....do this 3 or 4 times....

then
Install the carts...
open solution center.....click maintence tab...click on "clean to fix horizontal streaks"...

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The Black Lines are not due to to toner problem.
The Black lines ate same at the Page Location . If so the Problem may be with Drum Or Charging Unit Or fuser assembly. If the same problem continues Please take out and see the drum do not toch it . (Please Power off the Printer and disconnect all the cables. )

REgards
Rafique

Without actually seeing a print sample or the machine, my bet would be on the black print cartridge. Even though it reads a an acceptable level of toner, the cartridge itself sounds like it has developed a proble. 1. It's the most obvious 2. It't the cheapest place to start. If it does not correct the problem, you can still use it later. 3. It's the problem in about 80% of these types of cases. 4. I know it should be fine, but if things didn't go wrong, I wouldn't have a job! Let me know. If not we'll investigate further. Ed