2 DMEs fried from water getting into that little compartment. How do I fix that?

[Goku]

So I'm now about to buy my 2nd replacement DME because every time there is a heavy rain over night, water leaks into the DME compartment and fries the DME. I replaced the cowls on the bottom of the windshield where the wiper arms are as the previous ones were cracked and almost completely gone. Water is still somehow getting in through the top of that compartment but I don't know how or how to fix it.