I have an excessive amount of water that comes into the rear cargo area on the drivers side. I have tested with a hose and it seems to be coming in under the black plastic that covers the roof channel on driver side. This is a 2006 Mazda 6i hatchback. Is there a way to remove that plastic piece to investigate further, without breaking it so it can be reinstalled? Maybe a better question..... is that a one time installation item? Not re-useable?