THIS SOLUTION IS FOR AN OKI C3400N ONLY
As I'm sure you know, that blinking amber light indicates that:
- A toner lock is not fully "locked", or
- A toner is empty, or
- A drum is empty or near empty
The first question should be what does your C3400 monitor software tell you is wrong? I am assuming it said the black toner and/or drum needed to be changed - so you are fairly certain it is the black that is where the problem is? You may also have run the report from the printer that you get by pressing the "On-line" button and seen what is failing.
Assuming that is the case, and one or both of these signals an empty black toner, the problem may be in the new black toner cartridge. You can try this:
- Make sure the toner "lock" on all toners is fully engaged - assuming they are
- Open the top
- Lift out the entire black assemble including the toner and drum components.
- Keeping the assembly in the same orientation as you lifted it out, look on the RIGHT end.
- You should see two metal contact points, near the top at about the same level as the top of the toner.
- Just below these contact, you should see a small, rectangular hole - about 1/4" square.
- If you look in there you may see what looks like a small piece of black plastic that covers the hole from inside.
- If so, take a small pointed object (like a bent paper-clip) and gently reach in the hole and touch the small plastic piece on the inside that is covering the hole.
- You should be able to gently lift that piece of plastic UP.
- You may have to try lifting it a time or two, but it should stay UP if you have a new black toner installed.
- Once you have it UP carefully reinstall the assembly.
- Close the top and let the printer recycle.
- You may need to try this a couple of times to get the plastic to stay up on your new toner.
So you understand, here is what may be happening. That little piece of black plastic actually sits in line with a sensor in the printer that monitors toner / drum levels. When a new toner is placed in, that piece of plastic should be UP, so the sensor can monitor the level. As the toner gets used, the plastic liece gradually falls down until it completely blocks the sensor - indicating the toner is empty. That is how the monitoring software knows how to signal you.
This has worked for me several times - most especially when I tried using non-OKI OEM 'compatible" toners - but no guarantees this will help you