Sorry to say that I don't have a solution to your problem. I was wondering from where you got that first instruction. 'press off and pull out'?? Do you have like a service manual/CD for R129 or have you just heard about the removal procedure for this knob? I've been looking for such a manual/CD. That's why I'm asking.
Hope someone solves your problem!
Emil Ísterman, Stockholm - Sweden
MB SL500 -93 - Silver
MB 230CE -84 - Silver
MB 230E -82 - Yellow
MB 180B -59 - Green