I just recieved my carpet from JC Whitney

, but before I put that in, I have a problem I've got to fix

. When water gets into the "grating" beneath the window (where the windshield wipers are), water leaks into the cab. I can look in there and see that it is full of leaves and other junk, but I don't know how to get inside of there to clean it out and see if I can find where the leak is. What do I do? If I find the leak, how do I seal it?
Here is a picture of what I'm talking about.
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