Originally Posted by BWhitmore

Recommendation: you need to change your ignition lock and tumbler (the part where the key goes in) as soon as possible. If you wait until the key will no longer turn, then this turns into a major job as the ignition lock pin will need to be drilled out. Let me know what your email address is and I will send you a good step by step procedure to change the ignition switch and tumbler. I would recommend you replace it with a genuine Mercedes switch and tumbler with a genuine Mercedes key but hang on when you hear the price (about $340). After market is about half but will not last as long.