Brother MFC 9330 CDW and the mystery of the unwanted embossing marks (a.k.a. fuser replacement)

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Published on January 21st 2021 - last updated on January 22nd 2021 - Listed in Hardware Office


When my Brother MFC 9330CDW started to print papers with embossing marks (with the shape of a corn plant - but that may just be my imagination) on it, something was definitely not printing as it should.

But what would cause these horizontally re-occurring marks?

I publicly asked this question on Twitter and received good comments. At the end it turned out to become a real-live streaming troubleshooting thread.

Toner drum units and transfer belt check

The first thought was that there is something sticking out or laying on the transfer belt. After removing the cartridge (toner) units, the transfer belt unit can be lifted off and taken out of the printer. Although used, the transfer belt had nothing on or in it, which would explain these marks:

Brother MFC 9330 CDW transfer belt unit

Additionally to this, all toner/cartridges were checked that they correctly "snapped" into the drum units.

According to visual verification (and to comments on the mentioned Twitter thread) the problem must be elsewhere. 

Focus on the back of the printer

When I opened the back of the printer - this is where the fuser unit is placed - I immediately saw something which should not be there: Some broken-off pieces laying there next to the fuser roll.

Brother MFC 9330 CDW pieces in the fuser unit

I removed these two pieces. But the question is: Where did these pieces come from? From what part did they break off? This is where my focus shifted towards the "inner" roll of the fuser, the roll in black:

Brother MFC 9330 CDW defect in fuser unit

A look closer at the "shape" of this defect, seemed to confirm the "corn plant" on the printed pages. And due to the fact that this is a roll, the horizontal re-occurring "stamp" on the papers is explained, too. 

Replacing the fuser unit

A replacement for the fuser unit (Brother product ID LY6754001) was ordered for CHF 138 (USD 155 with todays FX rate) and I got it a day later (delivery times have certainly improved in the last decade!).

Next step: Replacing the fuser unit. Luckily there's a great video by Hermes Lara on Youtube which shows how to remove the fuser and place the new unit back into the printer. I strongly suggest to look at that video and do the replacement while watching it.

Note: The video is for the MFC 9340CDW, which is a bit newer than my MFC-9330CDW. But the pieces and the replacement methods are the same.

The printer without the fuser unit:

... and with the new fuser unit built in:

Brother MFC 9330 CDW fuser replaced with new one

Right after this, the printed pages looked correctly again!

Firmware update

Besides the replacement fuser was a note: It is required to update the machine to the latest firmware after replacing the fuser unit. As I already did this in one of the first steps when I tried to figure out the reason for the marks, I didn't have to run a firmware update anymore. But as of this writing in January 2021, the newest firmware version is:

Main Firmware Version: ZA
Sub1 Firmware Version: 1.10
Sub2 Firmware Version: Q1811192000

Reset the fuser counter

Now that the fuser was replaced, the printer still thinks the old fuser unit is in the printer. This can be verified by checking the maintenance info page on the printer's IP:

Use this procedure to reset the fuser counter:

  • Touch and hold the "Home" button for around 5 seconds -> 4 rows will be shown
  • Touch and hold the last row (even though there is probably nothing written in it) -> a number pad will show up
  • On the numbers pad (not the one in the display) enter the following combination: * 2 8 6 4 -> This will display the maintenance information in the display
  • On the display, set 8 8 -> this will show the "Reset-Fuser Unit"
  • Touch the "SET" key on the display, twice
  • Then touch the "Stop" key on the display
  • Finally, enter the combination 9 9 on the printer num pad (not in the display) and the printer will restart

I created and shared a video for this:


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