The best suggestion is to look at each window and try and establish the path where water will intrude. On some of my ports, the window is pitched the wrong way.
I made sure the small drains are kept free and clear. I drilled the holes a little larger so they would not get clogged.
On other windows that leaked it was a matter of where the sliding window was located. They are known to fail if they are adjacent to the side walkways. I have since removed the sliders and replaced with a solid piece of Acrylic with 3M 4000 as the sealant. It stays flexible and is UV stable.
Tom and Cheryl
1982 41' President