Hi. I have a glass shower door (hinged). The door is fine except that the glass panel has started to come loose and if I don't hold it up when opening the door it would probably fall out. You can see from the photos that there is some sort of black glue / strip of something inside the door frame which was presumably supposed to hold it in. Any ideas how to repair this? Do I need to get more of whatever the black strip is and stick it in? (it's probably obvious but I haven't a clue about shower doors!).