I had an old fiberglass bathtub that cracked so am replacing and noticed that the drain seemed to have a small leak as there is a little bit of build up at the joint as you can see in the photo. So I figured it would be best to just replace this at the same time since the tub is out of the way. But there is this plastic like hard compound stuff all over and nothing can be removed... Can anyone tell me what and how to remove this stuff and can I just break it free and yank everything out and then replace it?