Including my Model 01, I have had 3 keyboards with Matias switches and they all suffer from key chatter (a single keypress registering two or more times) to varying degrees.
This guide is meant as a second step when What to do if your keyboard seems to duplicate keystrokes or a key stops working isn’t sufficient, but you’re not confident enough with a soldering iron to take the final step of replacing the key switch. This will void your warranty and if not careful, could make the switch you’re trying to fix, not work at all. While I personally believe this procedure is relatively safe, proceed at your own risk!
Key switch terminology
Below is a picture of a disassembled Matias clicky switch. Each component may look slightly different on your model. From top left going clockwise, I will refer to the component as top housing, bottom housing, slider, tactile leaf, spring, contact plate and switch plate (the middle part of the switch plate being the actuator leaf).
How I believe permanent key chatter happens on Matias switches
This issue can manifest itself when the left stem of the switch plate, which protrudes from the soldering point, is attached at an incorrect height such that the right stem, which is supposed to sit planted through friction on a platform on the bottom housing, moves around whenever the slider pushes down on the actuator leaf. This repositioning of the right stem can cause the actuator leaf to oscillate and make multiple contacts during a single keypress.
My approach to fixing this specific issue
First you’ll need access to the internals of the problematic key switch. Use a keycap puller (a bent paper clip also works well) to pull off the key cap. To remove the top housing, you’ll need to insert a thin object into the gaps at the top and bottom of the switch, to push the bottom housing off the top housing’s plastic notches. A tooth pick (especially the flat wooden type) works well for this. Once the notches have been dislodged, you can use a tweezer to pull off the top housing. Here is a video of the disassembly being done.
Once you have removed the top housing and have access to the switch internals, lightly bend the switch plate (the contact plate sits pretty much fixed) using a tweezer and/or your fingers such that there is a distance between the actuator leaf and contact plate, and so that the right stem rubs against the platform so it isn’t likely to shift around. Since the left stem of the switch plate is soldered, you should be able to bend the switch plate by lightly pushing different parts of it up or down (as seen when looking down into the switch).
This process can require some experimentation. Basically, you’ll want to be able to push down on the actuator leaf (simulating the slider when the key is pressed) such that it strikes the contact plate, and returns to its starting position a distance away from the contact plate. While this happens, the right stem of the switch plate should continue to stay planted on its platform and not vibrate or slide around.
Below are two pictures from slightly different angles of two disassembled key switches. The left switch had major key chatter issues and has been fixed using this method. The right switch has been working fine from the factory. You can see that the left switch’s switch plate isn’t as straight as the right one, and that’s because I have bent it so that the right stem would sit planted on its platform.
Later in the above video, you can see the reassembly of the key switch. I find that with Matias switches, it works better to place the spring into the bottom of the slider on the assembled top housing, then angle the keyboard when pushing the top housing onto the bottom housing, such that none of the components slip off.
Once reassembled, the key chatter issue should hopefully be reduced or fixed entirely. I did this procedure on a very badly chattering “R” key (it would register 2-4 times on nearly 1 out of 3 key presses, making it very frustrating to type) and it’s been several weeks of typing without it chattering a single time since. If you are not this lucky, feel free to repeat the procedure multiple times until you get it right. Just note that every time you bend the switch plate, the metal becomes more and more brittle and at some point it will snap and you’ll be forced to replace the switch entirely.