If your ignition switch is like the one in my Dads '67 230SL it should be held onto the back of the steering lock with 2 or 3 machine screws. I had to pull the speedometer out to access the switch when it came loose in the SL.
In this case, the electrical contact portion of the switch loosened from the switch body - a more complicated repair if you don't have a new switch handy.

Happy Motoring, Mark

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DrDKW