Product review (3 stars): I May Have Bought The Wrong Filter
The original wick filter had a metal strip to help keep it upright. The WF813 replacement does not have the strip and when the wick is wet it slouches down into the trough exposing the rear grating of the humidifier body and lets air flow across the top of the wick. Perhaps I bought the wrong one. Despite the one-inch gap the humidifier still blows moisture into my bedroom, and I have to say this humidifier is the best of 5 I have bought.