Viermalvier.de, das Geländewagenportal Foren Marken talk Mercedes Automatikgetriebe 5Gang Defekt?

The shift rod seen from under the G only moves for P-R-N-D.
The 4-3-2-1 shift positions are all inside the shifter. The position is sent to the transmission electronically.

You need to take apart and clean the shifter. Not hard to do.