The mouse I use daily for many hours is Logitech’s MX Ergo trackball and I generally consider it the best trackball one can currently buy.

Unfortunately, after only a year or two of usage, the trackball’s mouse buttons no longer function correctly. When clicking and dragging, they won’t hold down the selection reliably.

The mouse buttons first broke in my private trackball, and later also the ones in my work one!

After just buying a new one when the mouse buttons broke the first time, I figured this time I wanted to try and fix the trackball myself.

Video recording

In this 27 minute video, you can look over my shoulder as I swap out the worn-out Omron mouse buttons with Kailh replacement mouse buttons:

The basic steps are:

1. Unscrew the outside Torx screws.
2. Unscrew the inside Philips screws.
3. Remove the PCB from the case and fix it securely for desoldering.
4. Desolder the switch: heat up all 3 pads as simultaneously as possible (add more solder → more flux!), then gently push down on the pins to make the switch fall out.
5. Cleanly remove all remaining solder, then insert the replacement switch, double-check you aligned it will on the PCB, and solder it.
6. Put everything back together.

Replacement switches: Kailh GM 8.0

The replacement mouse buttons I’m using are Kailh GM 8.0 from the Kailh Official Store on AliExpress, which are advertised as “ultra high life”. Even if their life span is also only a few years, I bought enough of them to probably replace them another 2 to 3 times per trackball.

The Kailh mouse buttons behave very similarly to the original Omron mouse buttons. The click is very satisfying now, and reminds me of a brand-new Logitech MX Ergo trackball. I wouldn’t call the Kailh ones better than the Omron ones, but maybe others notice a difference?

One interesting side note: I noticed that when wearing noise canceling headphones, it was very hard to tell the worn-out Omron mouse buttons from the Kailh mouse buttons. The difference really is mostly in the sound, not in the feel when pressing the button down!

Why is the MX Ergo so unreliable?

There is a 1-hour video by Alex Kenis saying that Logitech switched from 5V to 3.3V logic voltages, and this violates the minimum electrical condition for the Omron D2FC-F, which causes oxidation.

Indeed, when I merely opened the switches and cleaned them up with a screw driver, this seemed to help. But, opening everything up is so fiddly that one might as well solder in new switches altogether :)