drain gasket

Hello, I went to replace the rubber gasket on my tub due to it being old and cracked, but was not able to. Normally I would see some play downwards on the drain assembly to remove the old gasket somewhat effortlessly. On this tub, I noticed there was no play at all when I pushed down. I made an...

How can I fix this leak? Just replaced the whole floor and studs because of this issue. It's leaking at a notch in the fiberglass. Should I sand it down or use jb weld or both? Please, Any Help Much Appreciated...