Several times now, when I open the fluidics drawer, the tubing connected to the filter with the pinch roller attached, becomes disconnected from the filter and sheath fluid fills the drawer. Each that this has happened I reconnect the tubing and push it down as far as it will go, however, it comes off again a few weeks later. Has anyone else experienced this problem? If so, do you know what is causing the tubing to become disconnected and how can I prevent it?