Description - Transmission Shifter
The M-B Transmission Selector allows the driver to select the required mode for the automatic transmission with the choices being usually;
- Drive (with a choice for manually selecting higher or lower gears if required)
The M-B transmission shifter has a safety feature whereby it is supposed to remain locked in Park unless the proper key is in the ignition and the brake pedal is pressed.
Issues - Transmission Shifter
A common issue is that the Transmission Shifter becomes stuck in the Park position thus disabling the vehicle.
In case of emergency a stuck shifter can be moved out of the Park position using force:
DIY Fixes - Transmission Shifter
Transmission Shifter Stuck in Park
This DIY fix removes the offending pieces, but in doing so, defeats the brake/shifter interlock. This means that the car can be taken out of park at any time without having to turn the key on and/or depressing the brake pedal to do so. If you plan to leave unattended children in the car, this fix may not be right for you in which case you should replace the broken pieces to restore the safety feature to its original condition.
Detailed method for a 2003 S55 click here 
Transmission Shifter Removal From Centre Console
As an unsafe workaround the plastic piece can be removed entirely. It will be possible to move the shift lever at all times even with ignition on or off.
also refer to WIS 68.20 Center Console
Removing shift knob
- Unlock the shifter knob by turning conterclockwise on the chrome part of the knob until it stops, only 1/4 of a turn is necessary.
- Lift the knob straight up off the shaft. Do this in N position if you have large hands so when the knob is coming off of the shaft you don't hit the COMAND screen and center console.
Fixing loose shift knob
Incorrect removal procedure by trying to twist the knob, will damage the plastic core of the gear knob and knob will become loose. One way to fix a loose knob is to use type around the shaft. The idea is to build up some thickness on the shaft. Do not wrap anything around the chrome bezel area, it won't do anything but stop the knob returning to it's original locked position. Only wrap the top part of the shaft.
Dissecting shift knob
- Use cord to tie up the plastic core and to pull the plastic ring off.
- Pour in some alcohol in between the wood part and the plastic core. Alcohol will soften the glue. Tier it gently until it comes off.
- KEYLESS-GO button is attached from the bottom with two T6 screws.