;tldr If the caps lock on your old keyboard stopped working, try to install and use Karabiner-Elements. It fixed the problem for me.

The caps lock on my beloved Apple Keyboard Extended II I use at work stopped working recently. I tend not to type in ALL CAPS often, but sometimes I have to type ridiculous acronyms and caps lock is the key I need. Later I noticed it wasn’t working on the one I use at home.

There are several breakpoints, so I first chalked it up to hardware failure. These things are more than 26 years old after all.1 They also require a Griffin iMate adaptor to convert their ADB connections to USB. After I saw the problem on both keyboards, I knew something was up.

One of the updates to macOS Sierra 10.12.x broke it. This was a problem, but it was a software issue and software can be fixed. I found Karabiner-Elements fixed my problem. It enables user to remap their keyboard. You can do lots of cool stuff with this (like creating a super meta hyper key), but my needs are simple for now.

After installing the software, I opened the settings and set caps lock to caps lock. That was all it took to return functionality to my caps lock key. I added it to my Login Items (under Users & Groups in the System Preferences) and I’m ready to ROCK AND ROLL!

  1. That’s crazy to think about. Apple introduced the Extended II on Oct 15, 1990. It was discontinued in March 14, 1994. Source: Wikipedia