I have a 1955 Sunliner and today the ignition switch key would not go into the ignition switch.  After some juggling around with the key it finally went into the swirtch but now it will not turn on.  I have another ignition switch assembly but I need to know how to take the guts out (tumbler assembly) .  It looks like there is some kind of pin on top of the ignition switch that holds the tumbler assembly in place.  Any help will be greatly appreciated.  Thanks

Gary