My wall air conditioner sleeve is not level and water pools against the inside edge and leaks inside during heavy rainfalls-- it appears someone in the past attempted to fix this, perhaps with an epoxy (I'm not sure what the substance is). I've started scraping it off, but I'm wondering if I can use epoxy or some other substance to try to level out the base of the sleeve so that the rain water runs outside again-- any recommendations? See comments for pictures, couldn't figure out how to upload them in this post from my phone.