Another option is to ditch the humidifying unit that came with the humidor and move to gel or beads. They do a much better job of maintaining proper RH levels.
Personally, I use unscented silica kitty litter. It maintains a perfect 63% which is where I prefer all of my cigars, it's the same chemical makeup as the $20/lb beads, but it costs less than $1/lb! It also has the added benefit of maintaining active humidification, meaning that it lets out RH when needed and sucks in excess RH.