soft spot in roof

[Goodrving]

while washing top of my 05 monty, I discovered a soft spot right in front of the antenna. as far as I can tell by feeling its something like 12 inches x12 inches. I have sealed around antenna about yr ago, but have not seen any leaks inside. I know taking it to an rv dealer is gonna cost a bunch! I am thinking of attacking the job myself. Has anyone had this to happen? if so any suggestions on seeing what needs to be repaired? I am sure it will need some plywood replaced. any suggestions on how to proceed? how is the roof fasten down? any help is appreaciated

[exav8tr]

Jim, If it's not leaking, why mess with it? I might outline it with a marker and be sure not to step on it and check it from time to time to see if it's getting bigger