I want to chande my drum (brothermfc-7420) and i dont no how to change it

try cleaning the laser shield glass for cyan. you said you change photo and drum. Does that mean developer unit for cyan and cyan drum unit.

go online type in Brother MFC-7420 reset and follow details

Simply open the front cover.

Press the Options key on the control panel.
The display will show "REPLACE DRUM - 1.YES 2.NO".

Press 1 to reset the drum count.

Close the front cover.

This procedure wil work on the majority of the Brother MFC series of laser based Printer Scanner Fax Facsimile machines.

Good Luck and Thank You for using Fixya WheatlandServices

Reinstall the new drum unit, keeping the front cover open. Press OPTIONS. Press 1 when the display shows REPLACE DRUM? 1.YES 2.NO ACCEPTED. Close the front cover.

First you need to clean up the drum and inside the printer.
after that if still jamming paper.
you better check all the rollers and check the drum unit.
if possible, please chang the drum and that should be working fine.

Just need to clean up all glasses with alcohol and move the blue panel to clean the drum, after that sould be fine.

Check your owner's manual, and there's one in the install disk. It will show you where there are electric contacts inside where the drum is. You may have to take the drum out to see them. You're supposed to clean them with isopropyl alcohol on a q-tip. Don't get alcohol on anything else.

the only time i've seen the drum affect paper feeding is if paper jams in the drum unit. i would use your current drum until print quality decreases to an unacceptable level. it will not shut down, and you will not see a "change drum message." if your paper feed problem is centered around the cassette/paper pickup area, you can try cleaning your rollers with water and a soft rag, and also make sure your rear paper stopper in cassette isn't pressing too tightly against the rear of paper stack. best to leave 1/8" gap, otherwise paper will not lift properly to the rollers.

hth,
razors

take the drum out and clean the grid on the drum unit. this is called the corona wire in the grid

Why does the message "CHANGE DRUM SOON" continue to appear on the LCD display of my Brother machine, after I replaced the drum? Description: This message would continue to appear if the drum counter was not reset when you replaced the drum. To reset the drum counter, follow the instructions listed below. Open the front cover. Press the Options key on the control panel. The display will show "REPLACE DRUM - 1.YES 2.NO". Press 1 to reset the drum count. Close the front cover.