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Robert M.
Robert M., Consultant
Category: Printers
Satisfied Customers: 8731
Experience:  30+ yrs. experience in NYC computer industry working with PC and networks, banks, brokerage, legal etc.
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hl-4040cdn printer.

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I have an hl-4040cdn printer. The back sides of printed pages have toner smudges on them. Could this be caused by the belt unit? If so, can the belt be cleaned? It has about 62% life left.

Hi, I'm Robert and I'll be helping you with your printer question.


have you tried just blowing out the entire printer ? And a new cartridge. About 90 % of the problems I have had with excess toner are due to a faulty cartridge.


what do the pages look like ? Excess print in the wrong places are also a sign of a drum going bad and not sticking the toner where it is supposed to go.


I would also look at the waste toner box. That is where excess toner is supposed to go. If that is full it might go back on the page.



Customer: replied 2 years ago.

I have refilled the toner cartridges myself. rather than buy Brother cartridges

How do you "blow out" the printer?

If the waste toner drum may be the problem, how do I fix it?

1 blow it out by using a can of compressed air and pulling all the cartridges etc to get the entire printer.


If it is one color I might suggest that its time to buy a new cartridge to refill. there are a few moving parts in there including one that shoves the toner out in a smooth manner. if that breaks or wears down ( its only plastic ) than you are not going to get the toner going exactly where it has to go the way it has to get there.


The instructions for replacing the waste box are on this link


Basically you pull out all the toner cartridges and it is sitting underneath them and pulls right out


You can buy them for about 30 bucks from brother or a little over 20 from other places






Customer: replied 2 years ago.

I surmise that the problem could be one, or more of the following:


Waste toner box my be too full

Toner cartridges (may be faulty)


The smudges appear to reflect all the colors in the cartridges.


The drum is very new. There is no problem with the printed pages; only the backs of the pages.


Do you perceive that refilling the catridges myself may be a mistake?

I would look at the refilling them as a possible cause of the problem. I would not say it is a mistake. But any problem with toner can have a cartridge as a possible problem and the usual way to test it is to use a new cartridge.


are they smudges or dots? if they are smudges the most likely cause is a bad fuser. It should be hot enough to sear everything to the page instantly where it was put by the drum. When they get older they don't get hot enough fast enough and it takes a bit longer to bond the ink to the paper so it smudges as it goes through. They can also get cooler in one section than another so the sides would smudge but not the middle or vice versa

Customer: replied 2 years ago.

They look like elongared dots (or smears) running from the tops of the pages to the bottoms. They run intermittently dark to light in each of the four colors. They run from one side of the pages to the other; all on the backs of the pages; not the front

The printer diagnostics indicate the fuser has a long way to go.


I just now replaced the black toner cartridge with another one. The black marks still appear on the back of the printed page. Does that indicate it might be the waste toner box? (or fuser)

It sounds like the fuser to me. But I would certainly check the waste toner box.


the fuser replacement thing goes on page count. Things sometimes go bad before they are supposed to.

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