How do you replace ignition switch in Mercury Villager 1995 van?

2000 mercury villager..ignition key will not turn....for the 2000 the tumbler can not be removed from the housing which cost $200 + from the dealer and is riveted together on the column. If you take the plastic interior peices off the column ( 4 screws ), you`ll see the die cast assembly for the ignition, it looks like a cylinder on the bottom with a band or clamp on the top of column, with a large diameter rivet on each side.all I did was take a punch and hammer and give this assembly a couple of taps on either side til the assembly realigned itself , and I could turn the key . good luck