I have Danby dehumidifier DDR4010E and I can't remove the air filter. It slides out only 1" and I can see inside there is a notch that does not allow it to come out completely for the cleaning purposes. Earlier on the display I was getting a message PI and the 3 drops (high fan) light was on, fan blowing but not dehumidifying, and not allowing me to change any settings when pressing buttons. Please explain the error code PI and how can I clean the filter. There is no info in the manual. Thanks!