I hope the OP’s fix works. This might be something to try if it doesn’t.
My trailer had a window of that type which developed a leak on the upper corner. The problem behind the leak was that for ease of installation, the manufacturers make the opening significantly bigger than the window (obviously it has to be bigger). As long as the window is installed in the center of the opening, there should be no leaks as the corners are covered. Over time though, the vibrations and jolts can take their toll and the window can shift downwards. If this happens, gaps will occur at the upper corners, and water can infiltrate.
My fix was to install plastic shims beneath the window to prevent it from sagging. I made the shims from a piece of PVC trim I had laying around. When inspecting the window, if you see a gray shadow just above the top of black trim, then the window has probably sagged and it’s time to reset the window.
