I have the beads as well, and they usually keep things even. However, in the winter my house becomes *very* dry, so I have to add a bit of water to the beads. Then in the summer, because of temperature concerns, I have to move my humis to the basement. The basement is much more humid than the rest of the house.... so the beads are unable to reabsorb all the moisture.

So a little trick I do is to remove one of the cedar trays (and the moisute in it) from the humi, and take it out to my very dry garage. The next day I put the now-bone-dry cedar tray back in the humi, and it absorbs more moisture. That usually does the trick.