If you have the car running and in 1st gear but pushing the button doesn't make it go into auto,
there are 2 things that you need to check before you start panicking about a new SE Drive or switch.
Pull the gear knob off. Pull straight up, do not press the auto button, do not hit yourself in the face.
This removal is the same for all standard gear knobs and some Brabus ones.
With the gear knob off, look into the end and press the button. You should see a plastic peg emerge.
This plastic peg pushed the microswitch attached to the SE drive shaft. If the peg is broken, look here.
The peg on yours will be black, not blue.
There have been more and more reported cases of the Burgess F1NST8A1 microswitch failing.
Here it is below. It has 2 wires although it is a 2 position switch, only the "normally open" side is used.
Pull the microswitch out a little bit, you will see the 2 wires going to it.
If either of these wires are disconnected, solder it back in place and retest the switch.
Look at the metal arm that goes over the red nub, this is what transfers the movement of the gear knob
button to the switch. If the metal bar is deformed, it can bridge the red switch and stop it from being pushed.
Either reshape the metal bar or take it off and bin it. The gear knob button should still touch and activate
it but the metal bar does stop the red rubber switch cover from wearing out so it's not an ideal fix.
With the car running and in gear, bridge the 2 terminals very briefly with a short piece of wire or unfolded paperclip.
If the car shows an A for auto on the speedo, the switch has an internal fault and needs to be replaced.
You will need a Burgess F1NST8A1 (do a search, companies like RS will sell them).
Desolder the old switch and solder the new one in place. Hopefully it all works now.