I just did this a few weeks ago. I also had trouble. I could get the release tool inserted but no release.............

Finally, I used a flashlight to look carefully into the holes where you insert the release tool. It turned out the the ignition had to be almost at position 1 but not quite. By the way, position 1 was much further clockwise than I thought. Using the flashlight, I could see when the holes lined up with slots in the tumbler. (the tool has to slide through the tumbler slots to properly release the tumbler)

Hope this makes sense.

J. M. van Swaay

__________________
1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles