I noticed last night that the window sill under my Sharp AF S80MX is water damaged. This unit is 3 years old. I have read up, and noticed that this could be caused by a blocked drainage valve. I have looked beneath the unit and can't find a drainage hole. Where would this hole be located, and can I possible clear it without removing it from the window? I can't lift the unit, it's too heavy. I need this unit as I have heart and lung problems.