I'm trying to replace the drain in my bathtub (Just the part that screws in to the drainage pipe, not the pipe itself). The old drain won't unscrew though. I applied WD-40 and let it soak. Then I used the handles of some channel locks to stick into the drain and twist it out, but it was so rusty that with barely any force the piece I was pushing against broke. Has anyone run into this problem before and come up with a solution?