One Apple iie key not working

Welcome!

I saw one YouTube video that involved unsoldering, swapping a key cap, and re-soldering, but that seems both risky and difficult.

I agree. I don't have an IIe board here to compare, but many of the older style boards where the keycap sits on a little pedestal can stop working if debris gets under the cap limiting its motion. I'd first try canned air gently around the base of the key to see if you can dislodge anything. A soft pipe cleaner may also help.

This Applefritter post:

https://www.applefritter.com/content/restoring-apple-iie-keyboard

suggests that repeated rapid pressing and releasing a key may eventually dislodge crud around the keyswitch shaft or on the contact underneath.

Hello,

Recently a couple of keys on my Macintosh 512K’s keyboard stopped functioning. They use a similar key mechanism to the Apple //e. What I found was that the solder had cracked around the key mechanism’s posts. This meant that all I had to do was re-solder these posts to get these keys working without having to purchase new key mechanisms.

The process is not too intense with some basic soldering knowledge. What you would want to do is disassemble your Apple //e and remove the keyboard. Remove the bottom shielding. Use a soldering iron to heat up the solder around the 2 posts that are associated with the key that is not working. Use a de-soldering pump to remove any old solder. Add some new solder to these posts.

If your problem indeed was that the solder was bad then this should get you up and running fairly quickly. Worst case is you will need to purchase some new key mechanisms.

Here is a guide that includes some photos and techniques.

https://classic-computers.org.nz/blog/2015-12-27-appleiIIe-plantinum-keycap-replacement.htm