Black line down page when coping from copy feed

When you use the flatbed the copy is perfect because the ccd sensor is under the glass cover and obviously is free form dust/ dirt.
On the other hand if you use the feeder the ccd sensor is located in between the roller assembly (not sure exactly for this model).
This means that the page is scanned by the ccd in the feeder, any dirt on the ccd will appear as a black line. I assume that you are feeding papers from the side and not from the top that is why you get a horizontal line.

A quick test to see if the ccd sensor is dirty is to feed the paper from the top side to the feeder. If you get a vertical line it is a proof that your ccd sensor needs to be cleaned.
The worst case is that the sensor in the feeder assembly has a tiny spot that is damaged and it is causing the black line.
So , first try the test, then open the feeder assembly, locate the ccd and clean it. Hope that this helps.

When copying from the feeder the page is fed across a fixed point at the head of the flatbed. Any dirt etc on the glass at this point can present as a dark line running vertically down the printed page. When copying from the flatbed, the scan head is moved down the page so any dirt on the glass will only appear as specs. Try cleaning the glass, especially at the head of the flatbed where the feeder is loading the page to be copied.

It is the print head, change the cartridge.

Run a half test.
Put paper in the manual feed tray.
Print something, anything
When the paper is 1/2 way into the printer, open the cover.
Pull out the toner cartridge. Look down at the paper.
Does it have a black line on the right side?
If yes, replace the cartridge. If no, replace the fuser.

If this started after cartridge was replaced, then it is probably defective.

Take the cartridge out and take a look at the print head. Clean the print head.
Put the cartridge back in
Try and feed paper (not printing anything on it, if you can not get it to just feed paper, print a blank page) and see if it still has lines. If so, you are probably going to have to clean ink from inside the paper feed area. If not, try using it for a while and if it starts again, get a replacement cartridge. You might want to save some of the bad prints to show the clerk and try to get the new cartridge under warranty.

Most of Lexmark printers (including the Z- and X- series) pull the paper down on one side slightly faster than the other. The printer hardware should even this out when printing. You should also ensure the paper meets the automatic feeder requirements of the printer.

If printing is skewed, feeding multiple pages or jamming, please follow these instructions (use a regular letter size paper to test after doing the steps given below):

Please check to ensure there is nothing obstructing the paper feed mechanism down inside the printer where it is not easily seen. If there is nothing obvious, unplug the printer and remove the paper. Open the front cover and look above the steel rod. You should see a conveyor belt with rubber teeth on it, like a fan belt. Take the bottom part of that belt and move it gently to the left. The cartridges should come out with it. Make sure the cartridges can move fully from one side of the printer to the other. Check also the output rollers on the bottom of the printer for any blockage. If it is jamming under the carrier assembly, you may be able to fix it using the manual feed slot. Turn the printer off. Next take a #10 envelope and feed it through the left side of the paper feed slot (The manual paper feed slot is preferred, but the automatic feed will do if there is no manual paper feed for this printer) until it comes completely through the printer to the back of the exit rollers. Move it up and down and slowly move it over to the right side. If something is stuck under the black guide plate this may work it loose or you may have to feed the envelope through the front rollers and push your way backward (please be careful here).

Next, take a damp warm cloth and clean the rubber rollers in the automatic sheet feeder. Dust may be coating the rollers there and as they become less tacky, they cannot feed paper correctly.
Then plug the printer back up, take your paper out and replace it with a fresh, small stack (about 5 pages) of paper. Quickly bend the stack in an 'S' shape a few times to separate pages. Make sure it is lined up on the right side of the paper feed and the paper guide on the left is snug on the left side of the paper. Then try to form feed again. If that works, then try to print the self test page.

Please follow the steps given below to perform the self-test:

1. Make sure the printer is in “Copy Mode.”
2. Press the “Menu” button once.
3. The screen will display “Copy Menu: Copies”.
4. Press the left arrow button once. The screen will display “Copy Menu: Tools”.
5. Press the check button once. The screen with read “Tools: Maintenance”.
6. Press the check button once. The screen with read “Maintenance: Ink Levels”.
7. Press the right arrow button until the screen reads “Maintenance: Print Test Page”.
8. Press the check button once. This will start the Self-Test. Once the page has printed, the printer will stop. The test is not continuous.

The self-test should at least print out a set of either a solid black or solid color bars, if not both (if you have a printer with both color and black installed simultaneously). Should this test fail, please try it again without cartridges installed. If the self-test still fails to take paper in and make sounds like the carrier is moving across the paper, this is a hardware issue, and the printer will require service. If the self-test completes without any cartridges installed, run the self-test again with only a color cartridge installed (If you have both black and color cartridges, after this test, run the test again with just the black cartridge installed). If you find that either cartridge causes the self-test to fail, please let us know.
If the self-test prints, but has lines or smudges or other print quality issues, please let us know. This includes any print quality issues - we need to know if the problems you have with your black or color are based in the printer, or communications with your computer, or the computer's software.

If the self-test prints your test bar(s) clearly, the printer hardware is not at fault.

Most of the Lexmark printers (including the Z- and X- series) pull the paper down on one side slightly faster than the other. The printer hardware should even this out when printing. You should also ensure the paper meets the automatic feeder requirements of the printer.

If printing is skewed, feeding multiple pages or jamming, please follow these instructions (use a regular letter size paper to test after doing the steps given below):

Please check to ensure there is nothing obstructing the paper feed mechanism down inside the printer where it is not easily seen. If there is nothing obvious, unplug the printer and remove the paper. Open the front cover and look above the steel rod. You should see a conveyor belt with rubber teeth on it, like a fan belt. Take the bottom part of that belt and move it gently to the left. The cartridges should come out with it. Make sure the cartridges can move fully from one side of the printer to the other. Check also the output rollers on the bottom of the printer for any blockage. If it is jamming under the carrier assembly, you may be able to fix it using the manual feed slot. Turn the printer off. Next take a #10 envelope and feed it through the left side of the paper feed slot (The manual paper feed slot is preferred, but the automatic feed will do if there is no manual paper feed for this printer) until it comes completely through the printer to the back of the exit rollers. Move it up and down and slowly move it over to the right side. If something is stuck under the black guide plate this may work it loose or you may have to feed the envelope through the front rollers and push your way backward (please be careful here).

Next, take a damp warm cloth and clean the rubber rollers in the automatic sheet feeder. Dust may be coating the rollers there and as they become less tacky, they cannot feed paper correctly.

Then plug the printer back up, take your paper out and replace it with a fresh, small stack (about 5 pages) of paper. Quickly bend the stack in an 'S' shape a few times to separate pages. Make sure it is lined up on the right side of the paper feed and the paper guide on the left is snug on the left side of the paper. Then try to form feed again. If that works, then try to print the self test page.

Please follow the steps given below to perform the self-test:

1. Make sure the printer is in “Copy Mode.”
2. Press the “Menu” button once.
3. The screen will display “Copy Menu: Copies”.
4. Press the left arrow button once. The screen will display “Copy Menu: Tools”.
5. Press the check button once. The screen with read “Tools: Maintenance”.
6. Press the check button once. The screen with read “Maintenance: Ink Levels”.
7. Press the right arrow button until the screen reads “Maintenance: Print Test Page”.
8. Press the check button once. This will start the Self-Test. Once the page has printed, the printer will stop. The test is not continuous.

The self-test should at least print out a set of either a solid black or solid color bars, if not both (if you have a printer with both color and black installed simultaneously). Should this test fail, please try it again without cartridges installed. If the self-test still fails to take paper in and make sounds like the carrier is moving across the paper, this is a hardware issue, and the printer will require service. If the self-test completes without any cartridges installed, run the self-test again with only a color cartridge installed (If you have both black and color cartridges, after this test, run the test again with just the black cartridge installed). If you find that either cartridge causes the self-test to fail, please let us know.

If the self-test prints, but has lines or smudges or other print quality issues, please let us know. This includes any print quality issues - we need to know if the problems you have with your black or color are based in the printer, or communications with your computer, or the computer's software.

If the self-test prints your test bar(s) clearly, the printer hardware is not at fault.

When coping I have a black line down the left side of the page. This only happens when I'm copying NOT when I'm printing off a document from Word or the Internet on my computer. How can I get rid of this black line?

There is a small strip of glass on the left side directly under the edge of the scanner, About a half an inch wide. It has something on it.
May be very hard to see, use a strong glass cleaner or some alcohol and a regular piece of paper to clean it with.

It is possible that the guides in the paper tray have moved?

If they are universal trays (meaning they are not locked down to only use one particular size), they could have easily shifted, causing what you have described.

Try copying using a sheet of paper through the bypass tray, and see if the image is centered. This will at least narrow down the problem to a particular tray.