Have this and a Brother 4040. BOTH are producing random splatter dots. Mostly black, but a few cyan. Replaced the toner with OEM, replaced the drum set with OEM, but the spatters continue. Cleaned the drum with a dry soft cloth, cleaned corona wires, blew out inside with compressed air. Baffled. BOTH printers, same problem. Have not changed drum on 4040.

Did you replace the image unit for cyan and magenta, you don't replace the developer you replace the whole unit which includes the drum! Did yo use third party ? BAD!!!!! Replace the cyan and magenta image units with OEM cartridges

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

Take the toner cartridge out and try to turn the Developer roller ( the toner coated roller), if it doesn't turn you have a faulty cartridge. If the cartridge is OK, recheck the Magenta drum to see if the thin corona wire has been broken. You will need to remove the Cyan toners to get to the corona wire cover. If is damaged or broken, the whole drum will have to be replaced.

This could be a DC controller issue or and issue with the black drum unit. If you have replaced the Black Drum, and it still produces the same error after doing a print, then you will need to replace the DC controller PCB and possibly look at the power supply.

• replace your toner cartridges
  

Try reseting the toner cartridge via the operations panel.

Do this by opening front door and pressing clear/back button, a menu will appear, we want to select C-TNR-S or C-TNR-H depending on if you are using Cyan/TonerStandard or Cyan/Toner/High Capacity, so use arrows to go to correct one then press ok to select it, then a new menu appears, we want to select 1 and ok to reset, then it should just go back to cover open.

That should do it, have you tried it? as I think I told you the same before, I also need to know if you are using original brother branded toners or refill/remanufactured ones. You can reach me via this question

Steve

If you've taken the printer apart and cleaned the belt unit and everywhere else in the paper's path, then it is probably either a bad toner cartridge or the drum. Since it's multiple colors producing splatter, its most likely the drum unit. Try taking the drum out and removing all of the toner cartridges and then clean the drums and corona wires. If its still producing splatter afterward, you've got yourself a bad drum.

Gently pull the toner cartridge out. don't want to spill toner,,, inspect to see if all plastic has been removed. warning toner is super fine soot do not repeat do not vacuum it up ,,, messes up vacuum and puts dust in air,,stains clothing

Look at contacts on toner cartridge and scrub with old tooth brush,,, look at contacts of printer same same.

First off, this is a comment from a random person who may or may not know ALOT about these printers and toner/printer design in general. All toners are not designed to the same specification. Toner is a combination of plastic "pigment" and iron like shavings to make it magentically attracted to the electrical charges within the unit. Different toners conform to different grades and mainly size of the particles within the blend. The manufacturer doesnt only recommend that you use their toner to make them money, yes of course it makes money, but its because when the unit is designed it is designed to use a certain grade of toner, trust me if you put the non-branded toner vs the branded toner under a microscope you would see quite a difference. Often the non-branded toner is much larger in particle size (obviousely because its cheaper to make at this spec). This causes a variety of issues from excess toner not being cleaned off of developer rollers, IDT rollers, or clogging of toner dispenser tubes in the unit and the micro filters contained at the toner dispenser assy and developer assys. Also as for the issue not changing when switching to dell branded toner - the dispenser tubes within this unit contain up to 500-1000 pages worth of toner, making no change in toner you make immediately visible. Also depending on the damage caused by the previous toner, it may not be able to be fixed until all the components in between the toner and final delivery (drum cart) are replaced. In this case more than likely the toner dispenser assy, all developer assy's, and drum cartridge need to be replaced, and than be sure to stick with factory branded toner :)

Clean carona on drum. blue slidy tab, sounds like you are using non brother toner is that correct? Replace with OEM, Can also be worn drum

It can only be the drum unit or the toner unit, both are normal consumables, sound's like the drum is the problem to me I'd change that to fix.