Three of your colors print perfectly. The fourth does not. The screen names a single color — magenta, say — and announces "Replace Toner," and because one slot is complaining, the entire printer sits idle. On the TN810 platform this is how trouble normally arrives. These machines — the MFC-L9610CDN, HL-L9410CDN, HL-L9430CDN, HL-L9470CDN, HL-EX470W, MFC-L9630CDN, MFC-L9670CDN and MFC-EX670W. Each color in these machines carries its own chip and its own page counter, so each gets into trouble on its own schedule — and the fix almost always concerns that one cartridge, not the whole set.

One color has locked you out

When the display flags one color and the other three are fine, leave the healthy cartridges alone. Nothing inside these printers measures toner; the machine keeps a running estimate per slot, and once an estimate hits the ceiling for the size it thinks is installed, that color is declared finished — even if the cartridge was just fitted.

The remedy is to restart that one color's counter, and only that one:

1. Leave the printer switched on and open the front cover.
2. Bring up the reset menu. Touchscreen machines usually get there by pressing and holding the toner-level icon; on button-panel machines, press Secure and X Cancel at the same time.
3. Pick the color the screen named. Resetting a different color changes nothing.
4. Tell it which size is physically in that slot — TN810, TN810XL or TN815. The sizes section below explains why this choice matters.
5. Confirm the reset and shut the cover.

Two honest warnings. Brother varies menus and key names across models and firmware revisions, so your machine may label these steps differently — the manual's "Reset the toner counter" passage is the authority for your model. And on some enterprise machines an administrator's settings lock guards the menu; a reset screen that refuses to open points to that lock, not a fault.

If you would rather not reset at all, many models let you soften the behaviour instead: find the "Replace Toner" setting under General Setup, switch it from Stop to Continue, and the printer works past a counter's estimate; judge each color by its output — when it washes out, it has truly reached the end.

All four colors are complaining at once

Four cartridges do not die on the same morning. When every color shows an error together — typically right after a full set change — suspect something the four share before suspecting the cartridges themselves:

• The assembly is not fully home. All four cartridges ride in one tray; if it stopped a few millimetres short going back in, every slot can misreport at once. Slide it out, push it back firmly until it stops, and close the cover properly.
• Each new color still needs its own reset. Counters are per color, so a fresh set can queue up four separate warnings. Run the reset above once per color, choosing each slot's size as you go.
• The machine needs a clean restart. Power down, pull the plug for a full 60 seconds, and start again — this clears a stuck sensor state.
• Still stuck? Four cartridges do not fail together, so look for a shared cause: an administrator's lock on the settings, or a fitted set that is not really the TN810 family — other Brother platforms' cartridges are not recognized here.

Colors are coming out faded, weak or streaky

Sometimes nothing is blocked at all: the printer runs, but the pages disappoint. Work by what you see:

A single color prints pale while the rest look rich

1. Check Toner Save first. Found under General Setup → Ecology → Toner Save on most models, it deliberately dilutes output — and colors wash out before black does. Turn it off and print the same page again before blaming any cartridge.
2. Level the powder. Take the pale color out and tilt it gently side to side five or six times so the toner spreads evenly, then refit it.
3. Accept a genuine end of life. One color fading with Toner Save off and the cartridge rocked usually means that single cartridge is near its rated yield. Its three partners may have plenty left — replace the one color, not the set.

Lines running down the page in one color

1. Clean that color's corona wire. Pull the tray out and locate the coloured tab on the affected color's drum section. Slide it slowly from one end to the other a few times, then make sure it clicks back into its home position, marked with a small arrow. A contaminated wire is behind a large share of single-color streaks.
2. Look for loose toner. Powder dusted inside the machine or smeared on a cartridge body means that cartridge is leaking — a cartridge problem, not a printer problem.
3. Consider the drum section. Streaks in one color that survive a wire clean and a cartridge change point at wear in that color's drum section — see below.

Three sizes, one set of slots: TN810, TN810XL and TN815

The three sizes are physically interchangeable — any fits any of these printers, in any color position — and differ only in how much toner they carry:

You will also run into TN815XL and TN815XXL listings. In our catalogue those carry the same ratings as the TN815 row, so for reset purposes regard the three TN815 labels as a single size. Sizes can also be mixed slot by slot — most owners buy the colors together in our compatible TN810 four-color set — provided each reset names what that slot actually holds. Get the selection wrong and the warnings lie in one of two directions: declare an XL or TN815 cartridge as a standard TN810 and the ceiling arrives early, stranding usable toner; declare a standard cartridge as a TN815 and the printer trusts a 15,000-page promise from 9,000 pages of black (12,000 from 6,500 of color), printing on fumes and running that drum section dry.

"No Toner": the cartridge the printer cannot see

"No Toner" carries a different meaning: the machine searched a slot and found nothing it recognizes. Counter resets are useless here — this is about physical presence and contact, so work on the named color only:

1. Power off and open up. Open the front cover and draw the whole drum-and-toner assembly straight out toward you.
2. Lift the named cartridge free. Press the green lock lever on that color's drum section and take the cartridge out. While it is in your hand, compare its color label with the slot's: a cartridge in a neighbour's slot is never recognized.
3. Strip every trace of packaging. A fresh cartridge arrives with a protective cover over its roller area; any of it — or any seal material — left in place stops the cartridge seating fully and making contact.
4. Wipe the chip contacts. Polish the cartridge's metal chip contacts with a dry, lint-free cloth, and do the same for the contacts inside the slot where reachable. No liquids, nothing abrasive.
5. Refit until the lever clicks. Return the cartridge to its own slot, press until the lock lever clicks, slide the assembly back to its stop and close the cover.
6. Restart from the wall. If the message survives, unplug the printer for a full 60 seconds before powering up again.

Gone through all six with the correct color seated and clean contacts, and the slot still reports empty? The evidence points at that cartridge's chip — a defect for warranty, covered in the closing section.

The drum is a different part with its own clock

Every cartridge on this platform works from inside a drum unit: the drum places the image on the page, the cartridge merely feeds it powder. Drums are separate parts from the four toners, wear out over a far longer period, and keep their own counter with its own vocabulary — "Drum End Soon" and "Replace Drum" concern the drum alone, and no amount of toner resetting will silence them.

When a drum unit is swapped, its counter must be reset through the machine-info or parts-life area of the settings; your manual documents it under "Reset the drum counter." Never reset that counter as an experiment on a drum that stayed in the machine — you would erase the wear estimate while the wear remains, and the streaks will keep coming. We do not currently list a drum unit for this platform in our catalogue; if yours asks for one, match the drum part number in your manual when you order.

Frequently asked questions

Can I run different sizes at the same time — a TN815 black beside TN810 colors?

Yes. The slots are identical and each color is tracked separately, so sizes can be mixed across the four positions. The one obligation is accuracy at reset time: each slot's counter must be set to the size actually in it, or that color's warnings will fire early or late.

If a cartridge was only fitted yesterday, can its "Replace Toner" message be trusted?

Judge it by the counter, not the calendar. The message appears when a slot's estimate reaches its ceiling, and an estimate that never restarted at the last change will denounce a day-old cartridge. Run the per-color reset for that slot, naming the installed size, then judge by output: full, rich color afterwards means the warning was bookkeeping.

Does the "Continue" setting cover all four colors, or do I set it per color?

It is one machine-wide setting, found under General Setup on most models: switching "Replace Toner" from Stop to Continue applies to whichever color next reaches its estimate. Nothing is configured slot by slot; from then on, fading output signals a genuinely spent color.

How do I confirm which size is in a slot before resetting it?

Read the cartridge, not the screen: the size — TN810, TN810XL or TN815 — is printed on its own label. A TN815-family cartridge labelled TN815XL or TN815XXL counts as the TN815 size in the reset menu; in our catalogue all three carry identical ratings.

Will Brother refuse to service my printer because compatible cartridges are installed?

No. Under the Magnuson-Moss Warranty Act, a manufacturer cannot make warranty coverage depend on you buying its own brand of supplies — coverage can only be refused for damage the manufacturer proves a supply actually caused. Independently of Brother, every compatible TN810, TN810XL and TN815 we sell carries our own 1-year warranty with free returns for a full year.

Is that cartridge really empty? Decide in four checks

Before you order anything, run through these verdicts in order:

• The color prints full and clean right after a per-color reset. The cartridge was never empty; its counter was. Print on.
• The color stays pale with Toner Save switched off and after rocking the cartridge. That one cartridge has reached the end of its yield. Replace just that color — the other three are innocent.
• A slot still reports "No Toner" after reseating, contact cleaning and a 60-second unplug. That is a failed chip, not an empty cartridge — and if it is one of ours, a warranty case: our compatible TN810, TN810XL and TN815 cartridges carry a 1-year warranty with free returns for a full year, detailed on our shipping & returns page; support is available Monday–Friday, 9 AM–5 PM CST.
• All four colors faded together, gradually, over weeks. The set has lived its life in step; replacing the four together — the compatible TN810 four-color set covers one of each — restores the balance in one change.