This has been a steady problem with my Mini Vivi Nova as well. The center post/contact isn't threaded, it simply pushes in through a silicone grommet. And that's the problem. You need to pull it out a bit, but over time it works its way back in. It's a great little clearo.... when it works. When it doesn't, you have to empty it, take it apart and fiddle with it....over and over and over and....!