I had a simular problem to the guy who was on the show and couldn’t turn his MB key.
Here’s what I did. I sprayed penetrating oil into the keyhole (PT Blaster or whatever that stuff is called), and worked the key in and out… and then let it sit for a while, and since then it works fine. It only costs $2.19, it may not work for you but it’s probably worth a try.
If there is too much wear or a heavy key chain the tumbler may need replacement. The mercedes dealer can get a matching new key and tumbler using the VIN. It is more expensive than $2.19 but may be a more permanent fix. The new key will match the door and trunk locks. Worth the peace of mind IMO.
That’s totally a good idea. I just mentioned my solution because it’s held for two years, and he was looking for a do-it-yourself type repair, it a good first thing to try, then go for more expensive and complicated options. Take it to the dealer is always an option, it goes without saying.
Whenever I take my 1984 Mercedes to the dealer, I don’t feel the love, I feel the, “what can we do or say to get this rusty old thing out of here.”
My '84 Mercedes (280SE) also had an ignition problem. One needed to wiggle the key while turning - no amount of lubricant or new keys made any difference. Upon taking it to the dealer (for an unrelated problem) I was told that the ignition was broken, and they couldn’t start the vehicle. “Nonsense” I said, and went out to do my key-wiggling trick. This no longer worked! However, they were happy to replace the ignition, having broken it in my opinion, and for only another $200, now all of the keys work fine, and no more wiggling - hope this helps you.
I had this problem on my 93 civic, and I just took the ignition apart and removed the tumblers. Worked great. I could start my car with a popsicle stick. never had another problem.