I have a problem with a clogged trap that's located in a bathroom cement floor on the second floor of a 2 family that's over 100 years old. The trap is for both the old tub and sink. The cover is brass approx 4 inches wide with a hex nut and is threaded. This hasn't been opened in years and will not budge. Does anyone know anything about working with this problem? I'm concerned that this might become very involved.