keep trying before you remove the whole steering lock. if you get the pins in right with the right tool it takes about 30 seconds.for the top hole the pin slides over the retainer tab to disengage it. you can see how this works on your new tumbler that you have out. the other pin disengages a part that is a part of the steering lock behind the tumbler. that one push straight in and you should feel that it is slightly spring loaded when it bottoms out. when both pins are in place just tug on the key and the tumbler will come straight out.the only thing i can think of that may be going wrong is that in the upper hole maybe you're going under the retainer tab instead over the top or you're not going in far enough in the lower hole. keep trying. taking out the whole steering lock is a last resort when your key won't turn at all. or have some one with the right tool to take it out for you. I usually just charge people for the tumbler and no labor to replace it if it takes the usual 30 seconds. keep trying. I hope this helps.
good luck...paul

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Paul Roberts
Mercedes Centrum Inc.
Bellevue,WA.