Report "I have an SPT Dual Mist Humidifier, Model SU - 4010 that I purchased about 6 weeks ago. Initially, it worked fine, but, for the past two weeks, it doesn't always work. It will turn on, but at random times it will stop producing mist. I run it throughout the night and most mornings it is still more than halfway filled with water. Please advise on how to fix this"