I'm thinking it may be leaking past the glass/frame seal into the frame itself and out one of the screws in the bottom holding it together, running to that bottom corner. If it is the pane/frame seal, how would I go about repairing it or locate parts rather?
I had this issue as well, the rubber gasket can be replaced, I would add silicone to it before installing, obviously only on the side that is stationary.