Our Dell 3100CN printer blocks out a 1/2" wide line (all colors) print area on the right side. We replaced the printer drum unit and that didn't fix the problem. It was printing fine until we replaced the drum kit and a black toner cartridge about a month ago. We have since repleced the black toner cartridge. Still not working right...

Its the toner cartridges blocking the laser from hitting the drum unit. You need to remove each toner cartridge and re-seat it. It can drive you nuts. Steven 818-888-0006

Try replacing the toner cartridge. This seems to be a problem with the photo-sensitive drum, which is located in the cartridge.

Copied from the Dell community forums:

This is from a previous post and may help with your problem. I have printed 1000's since I came up with this fix with no recurrence of any streaking. Let me know how this works for you. I have come up with the cause and a fix for the above problem. This also fixes the problem of lines running the direction of paper travel on color prints. Black and white prints are OK. If you have a warranty on your printer or drum unit then you can have the drum unit replaced and hope you get a good replacement drum unit. To fix your drum unit do the following: 1. Remove the drum unit from your 3100cn. 2. Set the drum unit on a clean level surface and avoid touching the drum or the transfer belt (the decal with 4 arrows points to the transfer belt). 3. Remove the 6 screws from the top cover (the cover has the blue handle attached). Two screws are on top at both ends of the blue handle. The next 2 screws are on the sides and line up with the decal with 4 arrows. The last 2 screws are also on the sides and at the lower corners of the big decal that shows how to remove the drum unit from the 3100cn. 4. Carefully lift the cover from the drum unit and cover the drum unit with clean paper to protect the transfer belt from bright light. You can carefully reinstall the drum unit without the top cover and run some color prints. If the lines are gone then continue with step 5. 5. Look at the ribbed side of the top cover. Some may show some toner build-up. Some of the rib intersections are too high and are dragging in the toner that is applied to the transfer belt. The ribs are there to add stiffness to the cover and to keep it from bowing. 6. Place the cover handle side down on a clean towel. 7. Using a palm sander with 320 grit sandpaper and light pressure (the weight of the palm sander) sand until the ribs going both directions are showing signs of being sanded. You will be able to see the difference as unsanded areas will be glossy and sanded areas will have a dull finish. 8. Switch to 600 grit paper and do a light sanding. 9. Wash the cover under cool water. Don't use hot water since that could cause the cover to bend. 10. Dry completely. I used compressed air. 11. Reinstall the cover to the drum unit. Tighten the 4 side screws first and then the 2 top screws last. 12. Put the drum unit back into the 3100cn and try a color print. 13. Please post if you have any questions about the procedure. 14. If your next drum unit has the same problem you can swap top covers.

Message Edited by Ron13863 on 09-04-2007 07:16 AM

Sounds like a faulty black toner cartridge -- the clue is that the color is imaging correctly there (so the drum unit isn't the issue)

Refer to the following table
Cause
Solution
How common*
Contamination in the laser path
1. Clean the laser path. (Remove the laser/scanner assembly and clean the lens.) 2. Replace the laser/scanner assembly
8
Defective fuser.
Replace the fuser assembly
3
Lack of toner or faulty toner cartridge.
Redistribute the toner in the toner cartridge. If the problem continues, replace the toner cartridge.
7

Check to make sure that the locks on the toner cartridges are all the way seated. If they are not seated right they block the image from the laser to the imaging drum. All they have to be is a 1/16 of aan inch open and will do this.

Dell printers are junk. But you have put a lot of money into this thing. Check the alignment of the black drum, could be that something is keeping if off track a little bit.

This is caused by the imaging drum. This is a consumable item and needs to be replaced when print quality starts to deteriorate.

The reason the defects in print are always in the same location is because the imaging drum always starts at the same place, so the defect will always appear in the same location.

if any of the developers were defective, there would be many more defects, however they would be equally spaced between the defects.

REPLACE DRUM CARTRIDGE THE CLEANER BLADE IS BAD

Sounds like a bad imaging drum to me...