How to locate where a Master slide layout is used in a course.

I have a course that contains nearly 300 slides. I am trying to consolidate or delete some of the Master Slide Layouts. When I am in the “View Master Slide” menu and roll over some of the layouts, the pop-up text shows me how many slides use that particular Layout. From the thumbnail in Story View is was easy to locate most of the slides using a given layout. However, one layout still says that it is used on one slide in the course. I don't want to delete that layout for fear that one of my slides will suddenly loose that content but I won't know where. Is there any way to determine where in the course each layout is used? It is exhausting to go into Story View and right click each of the 300 slides to learn which layout is applied to that slide.