Oki C3400 ~ Dark Smudges Down The Page

This is a job I did for a customer’s Oki C3400 that had me scratching my head a bit. It would also affect the Oki C3300 and C3600 model printers as they take the same drum unit.

The following image is a copy of the fault and shows that the main colour affected is cyan (the blue colour) and to a much lesser degree yellow.

oki c3400 fault

As it turns out the drum unit is to blame. After striping it down for the second time I noticed the charge roller had some slight lumps on the end.

I then removed the charge roller from the drum unit and took the roller off of the chrome steel shaft. It was immediately noticeable that the shaft was the cause of this fault. Rust had built up on the shaft, causing the surface of the roller to become lumpy and cause serious copy quality problems.

rusty charge shaft

From there I simply used some fine wet and dry sand paper to remove the rust and chrome flakes.


With the shaft smooth again I simply slid the charge roller back onto the shaft and fitted it back in the drum unit.

c3400 cyan fixed

I then cleaned the yellow unit the same way as the cyan.

c3400 fixedA perfect copy!

This fault should only occur in printers that do low volume printing and have the drum units replaced infrequently.

Note: this job is a bit mucky, as to remove the charge roller you will need to take the top off the drum unit/toner hopper, so have some paper or cover sheets to work on.

A easier option for most people will be to purchase a new drum unit for the colour giving the fault

Easyink Support has written 90 articles

4 thoughts on “Oki C3400 ~ Dark Smudges Down The Page

    1. Easyink Support says:

      Hi Hugo

      The rubber sleeve will slide off with a little effort. I would put one end of the shaft against something solid and push the roller from the other end (note where the roller fits for re-assembly).
      Once you get it moving it should slid off quite easily.
      Good luck and please let me know how you get on.

  1. Harvey says:

    I’m just in the middle of stripping one of these printers to try and fix the same problem, the charger roller has noticeable bulges across it. There is rust at the end of the chrome rod and pushing off the roller (which is fun to do) has released a lot of rusty liquid.
    Now, having got the rubber off and cleaned the rod up, should the rubber be a “tight” fit to the rod? It fits snugly but can slighty move about.. does that sound about right?

    1. Easyink Support says:

      Hi Harvey

      It should be tight-ish (it will go on easier than it came off). If you are worried you could try gluing the roller to the shaft. Obviously make sure the glue is well dried before reinstalling the roller.
      I don’t remember it being a issue when I did it.

If you found this information useful, or have a question or suggestion, please comment below...

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>