I just completed replacing the ignition key tumbler on my '90 300te. I read all the posts and decided that this was a project I could do despite Ezequiel's troubles above. I spent the better part of 1 hour jiggling with coat hanger wire, and then I did a few things that made the job go just like that. Man, was I surprised when it just came apart. Here is what I did:

1. I decided to remove the padded knee piece that is just under the steering column. I know this step is probably not necessary, but I was having trouble getting a feel for the black collar and I felt like I was depressing the little tumbler clip and then when I would go to reach for the collar, the clip would snap back into place. This took all of 5 minutes with a nut driver, pliers and a screwdriver.

2. I examined the new tumbler carefully and it seemed like all I would have to do was insert my wire into only the top hole to force the clip down. I decided to take the advice of many threads and bend the wire into a U shape with appropriate 45 degree bevels. Then I inserted into both holes with one hand and used the other hand to gently apply CCW pressure to the black collar. The thing unscrewed within 10 seconds using this method.

Hope that helps.

Let us know how you do.