I purchased new and have used a GCX and Ground Control Pro for a couple of years. I love it and it's a very slick setup. I use it to control an OBEL effects loop with mostly vintage pedals and also use it to switch channels on my Mesa Boogie amps.
Last week channel 5 simply failed to work: no LED comes on when the footswitch is activated and the GCX channel doesn't switch (or light up either). All other channels work flawlessly.
Any troubleshooting advise or actions to resolve the problem would be greatly appreciated.