I just had mine replaced by my trusted indy MB mechanic. He replaced the tumbler, switch, and steering wheel lock. Parts were $270 with new key coded to the old key so I can continue to use just one key for both ignition and doors. Labor was 3 hours=$270. total $510. There is a write up in the DIY articles in this forum. Too complex a job for me. Mechanic confirmed it to be rather involved.