Please listen the holes in the cover are suppose to be there. There vent holes to let the moisture escape and dry the Hearing Aids. Do not cover the vent holes or the Hearing Aid Dryer will not be able to do its job because the moisture can not escape. The moisture will just fall back on the Hearing Aids when it's off and the air has cooled just like moisture does in a greenhouse. This hearing aid dryer is a little tricky to use but it takes some time getting use to it. The button is not a real button but a touch sensor button. Just touch it ones and it will flash red and green for a 3min uv dissenfecting and 3hrs for drying. Touch the sensor button again and it will flash red and blue for a 6min uv dissenfecting and 6hrs for drying. My hearing Dr recommend a new hearing aid dryer cause mine was almost 10yrs old and the tubes on mine became yellow from the moisture in my ears. This hearing aid dryer seems to be working because I'm not seeing any left over moisture in the tube when it is done like I did with my other aging hearing aid dryer did.