Diane, I feel your pain. I have a toilet like Joe Z has, and I appreciate his attaching the pdf on it. I have a leak where the bowl meets the tank. I'll try tightening the bolts (I learned that here) and if I still need a seal, I know what to order.
I just finished replacing the subfloor on my (new to me) '89 Casita
. The osb flooring or whatever it's called was spongy and the majority of the water was coming from a cracked shower drain. There were other small leaks
that, over the years, added to the mess. You'll have no fun fixing it, but it will be as new and smell a lot better when you get it finished.