Thanks iluvjesus.
The shifter module is now removed. It is a little different than the thread you referred to in that there are actually 2 more allen bolts on the opposite side from the ones I had marked. They were hidden under the left air hose to the rear air vents in the center console. I found it helpful to remove the rear center console, so the air hose could be removed and the module taken out, after removing the clip that holds it to the gearbox linkage and 3 electrical plugs at the rear.
So, the best order to attack it is: remove the gear knob, wooden trim with switches around the shift stick, then remove the rear part of the center console itself including storage box, then the air tubes to the rear vents, the four allen headed bolts (2 on each side), disconnect the gear box linkage, disconnect the three electric plugs at the rear of the module and lift the module clear.
When the module is out, it can be taken apart by levering the plastic clips on each side and the front. The two torx screws on the bottom do not need to be taken out. The electric switch is a push fit in the bottom housing and this may be the last thing resisting the two housing halves coming apart.To get the electric switch out you have to remove the two bolts that secure the axle that the shift lever rides on, then lift the axle and bearings out - make sure all the pieces stay together to be re-fitted!. Finally you have the electric switch in hand.
I sprayed contact cleaner into it and it seemed to make no difference! When reassembling it, I noticed that putting sideways pressure on the switch housing where the elecric connector is made the "D" light up and the gearbox shift as expected. So in the end, I wedged the switch body slighty to one side with a small piece of wood.
I think unless you want to replace the switch with a new one, this is the best approach.