Are there any Mercedes "key" gurus around? About 4 years ago I took over the W201 after my wife died. I've had it since new. Never had a key problem in any of the several I've owned. I had a 'sticky' key soon after I started driving it. Was in a locksmith's shop for something else and while I waited I overheard him talking about key problems with Mercedes to another customer. When my turn came, I asked him about a peremptory 'fix' on mine that was feeling sticky. He asked for my key and showed me a dismantled cylinder he had in his showcase. He claimed that the leaves in the cylinder don't cause the problems. The problem is caused by the rounding and wear on the edges of the key. Sure enough, my key was rounding severely. He cut another key for $35 and I've not had any problems since.

Is the rounding of the edges of the keys the cause of the problem, and therefore the key is the culprit? Or is it wear on the leaves in the cylinder. The leaves he showed me weren't worn and he claimed the key metal was much softer. The new key with the sharp edges seems to be the fix in my case.