"When someone tells me that a piece of equipment is not functioning correctly, the first thing I do is ask them to show me the problem. I will go to the area in question with that individual and ask them to talk me through the problem. If the problem isn't something that is easily observable (say an intermittent failure), then I will ask if there is any way to narrow down the problem. If all else fails, then I will ask for them to wait for the problem to occur and then call me directly, so I can come and help troubleshoot the issue.
This happened to me recently with a robotic packing cell that I had installed. The machine would alarm and stop intermittently, which required a team member to reset the machine. I wasn't aware of the problem until a team member told me about it. After asking the team member some questions and doing some investigation, we realized that an over current limit was set incorrectly on the robot. I asked a technician to correct the limit in the robot settings, and the problem hasn't happened since."