I have a 2017 Anniversario with soft top. The rear window has started leaking into the boot (trunk). I can't interrupt the opening sequence at the point where the bottom of the window becomes exposed, so I can't see where the leak starts. I know there's a drain in there somewhere, and perhaps it's blocked. I want to avoid taking the whole roof off to get at the window, and I'd also like to avoid putting sealant on the outside bottom of the window. Any suggestions? Thanks