Several Keys Not Working and Phantom Keypresses on Leopold Keyboard

[Faokryn]

Hi

I have a full-sized Leopold keyboard with Cherry MX Brown switches.  A few weeks ago, the 1, 2, 3, and Enter keys on the num pad stopped working intermittently.  At first unplugging and re-plugging-in the keyboard would fix this when it occurred, now they are consistently not sending key presses.  Also, starting earlier this week, they keyboard would randomly type "1"s, sometimes sending a single "1" along with a key press (space seemed to be particularly prone to this so that all my words in a sentence would start with "1"s), sometimes sending a constant stream of "1"s as if the key was being held down, and sometimes functioning properly.*

I have experienced these issues across multiple computers, operating systems, and USB cables; the only constant is the keyboard itself.

I've used a JavaScript key press detector to verify that only the four keys I mentioned aren't working.  I tried removing all the key caps, carefully disassembling the keyboard and dusting it with compressed air.  I then got out my multimeter and checked the 1, 2, 3, and Enter keys on the num pad; all appear to be working.  After "do electrons go through them when they're pressed?" I've exhausted my troubleshooting knowledge in this area.

I'm hoping someone with more experience will recognize these symptoms and can suggest a solution, or at least further troubleshooting steps.  Any help is appreciated.  Thanks!

* since disassembling and reassembling my keyboard, this issue has occurred significantly less frequently, but I've still caught a stray "1" or two :[

[merlin64]

Have you examined the soldered connections. I've seen electronics where the solder has just flaked off, or are just connected just enough to work. This usually happens over time. Sometimes its hard to see and allowing the solder to reflow might be better.

[mich]

Check if electrons go through traces connecting these keys to the controller chip. Check if some traces aren't shorted together or to ground. You may want to power up the keyboard while opened and measure voltages on these switches, compare that with working switches, see how the voltages change when you press some key, see what's going on when the keyboard thinks that 1 is stuck, etc. You should be able to figure it out with enough probing. Just be careful not to short two traces with the multimeter probe.