It is possible to do this but you have to cut the black cap off first.
Below is email we recently received from a customer asking for help:
Problem & Solution
Common among these chassis:
R107
W116
W123
W124
W126
W201
Hi, question for Kent. I have removed the black cap and then part of the cylinder fell off. Now the cylinder is in the "off" position and wont come out. Does the key have to be "on" to get the cylinder out after the black cap is off? It is unlikely I can get the switch to rotate again. See the pic of where I am. thanks Jim CSince he had purchased our kit with the video instructions our reply was as follows:Hi Jim, I hope you have watch the complete video that came with my kit. Right at the beginning of the video I explain you have to turn the key to get the tumbler out (that is true even with the black cap removed). To get the tumbler out without being able to turn the key he will have to grind the little square pin tower shown in the on demand video at 14:21. It is possible that your ignition lock assembly is also damaged and just replacing the tumbler may not solve the problem. Once you get the tumbler out if you can, try to turn the ignition lock with a screw driver inside the tumbler. You could even start the car with a screw driver if the lock and switch are working properly.Hope that helps, Kent Bergsma