If your lock set up is the same as mine (and make sure it is) then you'll want to see this:

http://www.peachparts.com/shopforum/tech-help/200554-1987-300e-key-stuck-ignition-post1640662.html#post1640662

I have a 1986 420. I need instructions & an illustration on the ignition cylinder lock removal . Thank you very much . Victross

Refer to the attached link. Scroll down to Bob Weir's post dated 5-26-2004 which describes how to remove the ignition lock cylinder and also fabricate the U-shaped wire.

http://www.peachparts.com/shopforum/tech-help/37927-190e-ignition-lock-broken-help-needed.html

Hello everybody.. My first post here.

Was very glad to find this thread after some intensive googleing. Have got the exact same problem on my -90 190E w201. Been sitting about 5 hours now and trying to get that stupid key to turn! Gonna try with vibratons on the lock this weekend though. Thanks for the tip!
Anyone else had any luck when putting vibrations against the lock?