Sunroof rear drain lines, exit location?

Have an issue--



My driver-side rear sunroof vent tube is clogged (Leaking water into cabin). I took the headliner down, tried blowing out the tube with compressed air-- but it didnt work.



I want to check the nipple at the end of the line, but cannot locate it. Does anyone know where it is located & the best way to access it?



thanks!