I used gaffa tape and plugged the hole. It's pretty much sealed, but the humidity is constantly sucked out of the beads and onto the back wall and into the tray I put there.Welcome! I have had similar problems with my cooler as well (though it's now under control). Make sure that the model you are using is thermoelectric as opposed to a model with that utilizes a compressor to cool itself. Also, make sure the drain is properly plugged (I have found that hot glue works wonders with this).