We have a leak somewhere in the top part of our kitchen window. It's a very large window, and the top part is a sealed unit with the window opening on the bottom portion. It only leaks when the rain is heavy from the North. There's 3 small section where the rain is leaking, but we can't see any kind of whole or crack on the outside of the house. The inside trim is starting to rot away and we're afraid to caulk from the inside for fear of rotting the inside of the wall. My question is how do we find out where the leak is? and who would we call for help in fixing this problem? Thanks!