My bathtub drain is running very, very slowly. Several years ago I had this same problem and hired a plumber. He cleaned out the drum trap and replaced the cover and charged me lots of money. I'm sure I could do this my little old self if I could only get the cover off! Any sugguestions? The nice new cover has a small allen wrench fitting in the center which I can turn with an allen wrench and the top lifts off about an inch or two. There is then like another cover inside which I don't know what to do with.

That's as far as I can get. I don't want to break anything. Help! I'm frustrated!