In the middle of my router control box I have a Pilz safety relay, bought cheap from eBay. New but obsolete model, box suffering from long-term storage but the device was fine and has been running perfectly for a few years. However, yesterday it refused to trigger when I hit the "reset" button. I have opened up the case but it's not easy to get at all the bits inside without dismantling with a soldering iron. I need to do a bit more testing before I go that far, but I wondered if anyone else has ever had a problem with one of these things, or has any other comments.

At least it failed safe!