<!-- from fixya rte -->Where do I find the waste toner box - Lexmark X543dn Laser Color All-In-One Printer

the top of the waste toner container must be cleaned 100% from the toner because it should be a light sensor that has to pass through it , if its spoiled with toner the light cannot pass through it ,so i recommend you to empty the waste toner container first and wash it with water and drying it well before using it again.

Typically you will need to replace the waste toner box. There is usually a difficult to access part of the bottle that is used by an optic sensor to tell when the box is full. Plus toner is very fine and you do not want it getting into the air. Toner will pass through the filter of most vacuums and go back into the air.

Remove the full waste toner box per manual. Wear breathing protection as there will be toner dust in the air. Place flat in a work area and remove the 6 screws retaining the black box cover and carefully remove cover with box still flat on the work area. Be careful, the box is full of waste toner powder. Dispose of the waste toner by tipping into waste container, being careful not to inhale the powder. Use a blower or vacuum to remove final traces of waste toner from the box and clean all surfaces with a clean cloth. Place the box flat on bench to inspect the clear sight-glass at the front. Inside will be a black flag which should be down on the bottom of the sight glass. If not, there is still waste toner in the front of the box which needs to be shaken or blown out. Replace the cover and 6 screws and replace the waste toner box in the printer. If error message still says replace waste toner box, then you need to check the sight glass again. The flag must be horizontal at the bottom of the glass or it is not completely empty.

Waste toner motor. Remove the Waste toner box and transfer belt ensure the waste toner box is not jammed up and check the transfer belt toner removal section is OK. Also check the gears on the left side of the waste toner box is ok and the machine gears ok not jammed. could also have a jam in the internal tube that runs the old toner to waste toner box get a tech out to check

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When you removed the waste toner bottle, there is a sensor inside the copier. When you remove the waste toner, look to the opening where the top of the waste bottle was, clean that area and return the bottle and turn the copier OFF then ON. Good Luck

REPLACING THE WASTE TONER BOX
The waste toner box collects residual toner that is produced during printing. When the used toner box is full, the display
will show "Replace used toner container". Follow the procedure below to replace the used toner box.
Open the front cover.2
Release the used waste toner box.
The waste toner box will fall forward as shown.
Gently support the box with your hands as you let it fall forward
as far as it will go.
Remove the waste toner box.
Hold the box by both hands and lift it up slowly.
If the waste toner box falls too far forward, it will not be possible
to remove it. (Remove the box when it is at an angle of about
30 degrees.)
Install the new waste toner box.
Insert the box from above at a slant. (The direction opposite to
when you removed it.)
Push the waste toner box into the
machine.
Push the box in until it clicks into place.
Close the front cover

Hope this helps.

To replace the waste toner box, open the front door above the paper drawers. The waste toner box is on the left hand side (usually). Your supplier should have supplied an extra waste toner box. Slide out the 'full' toner box. Replace with an empty one. This should register that you have installed an empty waste toner box. If not, turn off the copier and after a minute or two, turn on the coper again. [If you want to be environmental friendly, the toner box has a small slide cover approximately 1-2cm long (usually on the upper face at the rear as you remove it). Place this end in a plastic bag, slide open this 'cover' and rotate the toner box 180° so this is facing down. Care needs to be taken to prevent the 'waste toner' from flying everywhere. Gently agitate the box until all the waste toner (a grey color) has spilled out. (Approximately 600-800gms) Carefully seal the bag and dispose. An industrial vacuum cleaner can be used to remove the residual toner, clean down the waste toner box with a soft rag and it is ready to re-use.]

Remove the developer and toner cartridge from the front of your unit. This will allow you to take out your drum where your waste toner box is. Once you have your drum with your waste toner box make sure to detach the waste toner box from the drum. Take a damp linen free cloth and wipe down the inside of the drum unit where your waste toner box goes in. Now take your waste toner box and make sure to secure the waste toner box really well to the drum. This has to be in very tight or else the printer will not think that there is a toner box attached the drum and this error will continue to appear. Important thing is to make sure that the toner box is attached really well to the drum unit.

When you open the door to access the toner and waste toner area, you will see a letter "K" on the left side of the waste toner box, and a thumb screw on the right side of the waste toner box. Immediately above the letter "K" there is a raised area in the brown plastic housing. It is between the blue toner cartridge, and the waste oner box. There is a second raised area 2.5 inches at a 225 degree angle below the thumb screw on the right side of the waste toner box.
If you will place your thumbs on the raised areas and your forefingers on the white plastic rear cover of the waste toner box immediately below the raised areas and squeeze your fingers towards your thumbs, the waste toner box will come forward at the top of the box. You can then lift the waste toner box up and out of the printer.
Please squeeze carefully if you think your waste toner box is close to full as you may inadvertently find waste toner all over the place.
The two blue caps on the back of the waste toner box are to keep the waste toner in the waste toner box instead of your carpet.
Installation of the new waste toner box is the reverse of the above procedure. The new waste toner box almost snaps in place.
Here in California waste toner is considered a hazardous material and must be disposed of properly.