Hi all, and thanks for your responses.

Bob, right you are about the SO! I think I'm going to try to patch it
up with tiles we got that are pretty close the the existing ones. The
only issue I have that I'm not sure what to do about is that there is
no existing membrane. Would you recommend I put in my own? If yes,
then what am I attaching it to to make sure it's sealed sufficiently?

Again, thanks!
Philip