Originally Posted by MB-Dude

I'm assuming you are talking about the key tumbler in the ignition switch. Hmmmm.... I'm not familiar with a '90 190E, but I have taken the tumbler out of a '79 240D. You do need to make sure the wire is quite stiff, so as not to bend or flex inside the tumbler. I used a very Jeweler's Screwdriver. Once you insert the key, ensure you push hard on the wire as the locking mechanism may be sticky. You have to push the wire, jiggle the key, and pull the tumbler all at the same time. Once the tumbler started to come out, it easily slid out. The tough part was overcoming the internal lock. Perhaps the black cover you see is not stopping the tumbler, because you are not pushing hard enough on the wire.