Some keys of your UHK may start to produce repeated keystrokes over time, or may not produce keystrokes at all. It's generally due to a physical issue of key switches, usually due to a bit of dust. If this occurs, please remove the keycaps of the affected key switches (possibly with a DIY keycap puller), and spray contact cleaner spray into them while pressing them a couple of times.
If the above doesn't help, the affected key switches must be replaced.
If you have basic soldering equipment, and want to fix this yourself then you can disassemble your UHK, then desolder the affected switches, and solder new ones. If you choose this route and your two year warranty is still valid, then we'll gladly reimburse your expenses, such as key switches.
Alternatively, if fixing things is not your cup of tea, and you're still covered by our two year warranty, then shoot us a mail, include your order id, and we'll replace your UHK.