The W210 that has the problem of the key not turning turns out to be the shift lock cable being out of adjustment under the center console by the shifter.

Not the tumbler.

Unfortunately the steering lock locked up with a loud bang when removing the key / switch mechanism.

The car may be a brick now.

There is a procedure to unlock the steering lock where a hole is drilled in exactly the right spot and then hook the locking pin and pull it to the unlocked position.

If anyone knows where to drill or has a picture of the hole location on the back side of the steering lock may save the car.