I need to remove the knob on my 2000 ML to replace the window switch assy. The instructions given Simple Web Page here say to turn the black plastic retainer at the bottom of the shifter and just lift up on the knob. The 2000 must be different. Turning the retainer just allows a plastic cover to drop down. Under that is more plastic, looks like a nut with spanner slots. I can see threads in the chrome shaft. I tried turning the bottom nut but nothing wants to move. Any ideas?