Drum error: slide the green tab on drum unit on each color

SOURCE: drum error : slide the green tab on drum unit in each colour?

you forgot to slide the tab, unless you do this you cannot use your printer im afraid, drum unit is a cylindrical part unit, unless otherewise you correct this instlltion procedure there is no othere way around it
cheers

SOURCE: Brother 4070 CDW Drum Unit Error

The green tabs that you have to slide are under the color cartridges, so remove the three color cartridges and you will see three green tabs, to slide the tab across the wire you have to first open the translucent plastic wire cover, then slide the green tab across the wires and return it to it's original position, close the wire covers, replace the color cartridges, and reassemble the printer. All the Best

SOURCE: Our Brother HL 4040 CN

since changing the drum for brother hl 40-40CN , the printer won't work.

SOURCE: brother HL 4050 CDN suddenly

The green tab slides from left to right.
This cleans the croner wire. These wire also have a tedancy to break every often.
The drum unit will need to be replaced

SOURCE: my brother MFC9840cdw has an error message that

The guy that replied solved the problem. He rocks and I can't believe that brother does have a large posting on this issue. Sham on them:
ben2913 did the job "This is NOT the solution to this error code. The code is telling you that the Corona wire must be cleaned. Remove all 4 color drums. Look down into the tray that you removed them from and you will see 4 green tabs. Open the plastic cover that protects the corona wire and move the green tab back and forth several times. After you have done this with all 4, reinstall the drums, close the machine front and everything will work fine again."