Well after our recent rainstorms, I noticed some water in the corners of my rear shelf. So today I got up and cleaned them out. Outside of the dirt and leaves that I removed, I also removed some drywall screws, a sunglasses lense, and an 8-ball keychain. Needless to say they are draining better now. It didn't take me as long to find the lower drains as I thought it would. :D