I asked about fitting a Led into the dimming mirror but no one had done it or knew how to do it.
So as it was raining and I had some time (Fatal lol) I decided to take the mirror apart.
The mirror is clipped together very well and expect to break a few clips (They are inside so it doesnt matter). I used a couple of butter knifes and 'prised' the two halfs apart.
Once open the mirror and pcb come out as one, the led that points down is mounted in a pcb on its own that slides out of the housing. Then just replace the led
Few pictures for others: