I’ve replaced many tub/shower washers, o-rings and valve seats, but I just pulled the backing plate off some shower handles, and the escutcheons and stems are completely buried in plaster with some sort of silicone sealant. I’ve never seen anything like this. Am I supposed to chip away the plaster? I tried to turn the escutcheon thinking in might break loose, but I think I would have to destroy it to get it out.