Ignition switch, problem screw? HELP!

[eightball]

I have been told my ignition switch is about to die, it makes an sparking noise as I drive along. By ignition switch i mean the black cased unit which the key barrel turns as the actual electronics for the car start. The haynes manual says to remove the screws holding it in. The screw facing towards the driver is just a flat head screw driver job and comes out. The screw on the opposite side is a mistery! I can't seem to get anything to fit it. I have tried torque bits and alan keys, but nothing fits snugly. I thought the torque bit did, but when it turned i could feel it was slipping over whatever is there. Does anyone know anything about this/ had the same problem? I'm thinking about cutting the old unit out some how and trying to turn the screw with what ever thread is available from the inside with some incredibly thin nose pliers, but obviously this is not great and could end in tears.

Ian

[Octane2097]

could be someone had tryed removing it before you and knackerd the head on it.
its not somthing i have tryed to remove before, maybe try looking in a haynes manual
sorry i cant be any help buddy

[scotty cav turbo]

Are you on about the ignition barrel itself your trying to remove??