Drum at 53%

If the lines go all the way down the page, check the position of the corona wire cleaner tab (blue or green) at the top front of the drum unit. if not parked fully to one side it will create a solid black lines where it blocks the laser. Otherwise look for some other foreign object (or torn paper piece) that may be blocking the laser from the drum. If the lines are thin and shark, check for scratches on the drum (not repairable without replacing drum). If the lines are uneven thickness but in a pattern that repeats down the page every few inches, then the film on the drum is probably worn or wearing away and the drum needs to be replaced.

It is probably the toner cartridge, not the drum. I suggest swapping in old toner cartridges and drums to nail down the problem. I keep at least one old toner and one old drum for that purpose. By the way I just bought a toner cart from monoprice.com. It will not last as long as a Brother cart, but costs very little.

Needs Drum If you pull the drum unit out you will see on the drum different shades of color lighter is wear the lines come from. Buy a rebuilt drum much cheaper and they work, may have to reset the drum count if the change drum lite on...

the line could be caused by a scratched DRUM unit or a contaminated trasfer roller... And the shadow is probably a broken MICA ROLLER in the FUSER,

To get rid of the line (if the drum is OK) you need a mantenance KIT for that model, (pickup roller, transfer roller, separating pads etc...), for the shadow you need a new FUSER

Cheers!

It is possibly the drum unit.

If you have printed around 10.000 pages with the drum, you should consider replacing it.
Take a look at the black cylinder. (Where the toner connects to the drum) It should also have the same line on the right side.

You can try cleaning the cylinder with a soft kitchen roll or tissue. After that the printing should be normal. If the printing is still not normal, or is normal for just a couple of pages, you should change the drum unit.
If that also does not help, then the fuser unit within the printer is defect.

It is probably the transfer corona if you have already tried replacing the toner cartridge. The transfer corona charges the paper so that it will pull toner off the drum and it can go bad. Email HP and find out if the transfer corona is included in a drum replacement. If so, you need a new drum. If not, see if you can purchase and replace the transfer corona.

See its a very common issue.the right side of the drum has moisture on it.remove the toner and drum and apply a hot air blower on it for some time also clean the printer internally.reinsert the toner and drum.
check by printing few pages the smudging on the right should go within 10 to 12 pages.
if the smudging doesnot go away then its time to replace the drum to solve the issue.

This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya.

All blank pages could either mean: On the scanner side: * Mechanical error, you'll need to perform service on it to reanimate it again. * You can check if it is on the scanner side by printing a test page on the printer. If it prints fine, the problem is in the scanning process.
On the printer side: * Dirty connectors between toner/drum unit and machine. Remove the toner/drum package and clean the metallic cylinders on the left and right side of the toner/drum unit, then reinsert package into machine. * Bad toner and/or drum unit. Replace should solve it. * Mechanical error, you'll need to perform service on it to reanimate it again. * You can check if it is on the printer side by either scanning to a connected PC or sending a fax to someone. If the scanned/faxed page looks fine on the pc/fax that receives the fax, the problem is in the printing process.

The problem is that the revolving drum doesn't contact the OPC drum proberly. You have to open the left side off the machine and replace the little white gear on the shaft that drive revolving drum. The gear has "jumped"one step and the revolving drum isn't parallell to the OPC drum. I fixed my 2840 last night it takes some time but now it works perfect.

Time to think about replacing the image drum unit. Excess toner is not being cleaned off properly and is winding up on your printed pages. The drum unit is separate from the toner cartridge, and you normally replace the toner cartridges several times before needing a drum. Replacements are available from many online sources and at office supply stores. Generic replacements run around $50 and the original part is around $100.