Ink Leaks My MFC-420cn works well after I refilled all the ink cartidges. However, upon inverting it briefly, I had some leakagefrom the area to the rear of the cartridge area. It was blavk ink. Upon removing the black cartridge, I noticed that the cartridge itself in not leaking or messy. Is it just that the machine should never be inverted or is something wrong? Thanks

Refil Kits dont always work, you made need to buy proper ink cartridges.

I often have the same problem - The inks being put into the printer are seated very sensitively. The lever holding them in may be also acting as a pressure sensitive switch because when I wiggle it a little, the printer usually starts working again! Make sure the cartridges are pressed STRAIGHT DOWN, wiggle them and wiggle the plastic pressure lever. (I do not know what else to call it!) and I hope yours works again. It is a great little printer, but this is really annoying! Good luck!
BTW, if your inks are RE-FILLED, that may be your problem. It seems they are made to NOT be refilled. To avoid this problem, do not wait till they are empty to refill them. Check them monthly (depends on usage) and when they get 1/2 way, refill then. Do NOT put the hypodermic refilling tube in deeper than necessary to refill. I use a heated nail to make my hole in the plastic, going ONLY in as far as necessary to make the hole, and then I cover it with scotch tape. Then I wash off my hands with Lava soap! (Haven't mastered the knack of not getting the ink on myself, yet!)

Hi there you can refill Brother cartidges, like other printers it will not have it sorry.

This is the only way you can trick it.

There are only a few steps you need to do to reset a Brother printer ink cartridge and once you do it, you will be up and printing in no time. There are actually two things that a Brother printer uses to detect ink and you can manipulate one or the other.
Instructions
Things You'll Need: · Black electrical tape, masking tape or duct tape
1. Step 1
Identify the printer If your printer uses memory, you can tell which printer you have by looking at where the cartridge goes in, if you see two "eyes" and a part of the cartridge goes in between them, follow Step 3. Otherwise, continue with Step 2.
2. Step 2
Clear the memory by taking the cartridge out and unplugging the unit for 30 seconds. Then, plug it back in and put back in the cartridge. You may need to do this five times, as the memory holds the last five cartridges.
3. Step 3
If the Brother printer has "eyes" where the cartridge goes, you will need to block in between them with a piece of tape so that it thinks the cartridge is always full. Simply put a piece of tape on the piece of the cartridge that goes in between the eyes to block the path of the infrared beam

Please come back and just gave a vote, it will gave me some satisfaction to know am helping some one so I will keep on helping.
All The Best: Pineworks

At 1 of the end sides of the cartage you will see a little window, a beam of light hits that window to determine if you need Ink..Place a small piece of Electric tape over that window and.wallah print,fax and copy away. Brother is a ripoff-A cheap printer that auto-cleans(wastes ink) and locks the whole system claiming your out of Ink or low>>>But this is sure to work! ;)

Depending on the price you paid and how old the printer is, it may be time to get a new one, or it may just be a faulty ink cartridge, especially if you have tried to use a cartridge refill kit.

Try to take both ink cartidges out and clean up around the tray, if upon inspection of the cartidges, you see ink out side, replace em and see if it occurs again with new cartridges.

Cheers,

I wouldn't recommend refilling cartridges anymore. Nowadays printers come with a sensor which tell it which cartridges were used and refilled. Also do not use generic cartridges. Always buy genuine cartridges. Will save you a lot of headache in the long run...Trust me.

Above link great.
If you have a newer print cartridge cart, look for the little window. I put a sticker over the little window on the Brother (innobella) LC38 cartridge cart and it worked great :)
Despite finding a fix for this problem, I think this is a rip off setting on the brother printers and I will never buy another Brother printer for this reason.

Did you stich into the ink inlet within the cart holder with a syringe for pressing some air into the tubes? Never do that! Because you have dissolve the bottom of the cart holder or drilled a hole into the bottom.

The cart holder leaks and the poured out ink has already stained the whole machine!

The bottom of the cart holder is a foil which has been sticked onto the hard plastic (clever , eh?). This also happens due to the use of  a wrong refill ink or wrong generic carts the wrong mixture dissolves the foil and ink runs out into the machine....

You need a new cart holder to fix that.

Drill a 2 - 3 mm hole into the brother label upon the carts. Refill the cart which the printers display shows EMPTY. For color C/Y/M refill a 12ml and for black a 20ml ink. Use only dye ink! See pictures how to do that: http://www.hstt.net/refill-faq/brother.html#LC-900 Refillen

If you don't have the cartridges seated properly you will get this message. Pull them and try again. Myself, I tried to save some money, and bought Brothers refilled ink cartridges. They wouldn't work, so only use new Brothers ink cartridges. Unplug the printer from the wall for it to recycle, don't use the power button. Good Luck