if the distributor is still installed, wiggle the rotor while pulling the housing toward you.
the worm geas (s) provide resistance, just be patient, mine was the same way and eventually it wiggled off.
also, if you clean up the motor before replacing the housing, make sure not to paint the pins or the holes in the distro housing.
the fit is very tight and any paint will prevent you from re installling
when re installing the rotor will turn when the gears engage, you will have to set up the distro housing to your liking, the number one mark may not be in the same position
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230