A postscript... Despite having the same part number, the original and replacement halves of the switch are slightly different. Having reunited all of the replacement switch with the original housing, both the LED and levelling now work.

The only other thing to mention is that the springs on the multi-pin plug needed gently pushing out to make the contact good, which I am guessing could have blown a capacitor(s) on the original PCB, therefore making the LED inoperable (which tests ok on a meter).

Only the odometer bulb to go... ...and the leaky roof and front wheel arches! Thanks all for your help.

Just to update this in case it helps others.....,the little so called led,is in fact a very small bulb on my 2004 facelift D2.As a temp fix I have soldered a 286 bulb(much taller,but still only 1.2watts,height clearance inside the switch is not an issue).The leads of the 286 bulb are not easy to wett out with solder ,get the leads bright and shiny first and use flux and repeat before soldering to the pcb.Mine is working fine but I will try and find the proper bulb as the solder joints on my repair are not brilliant for long term reliability.

Disco1BFG said:

Thinking about it, the ON bit isn't quite right - slip of the tongue and all that - it should be IN - cos the little bar steward tin worms eat chassis / box sections from the inside out

Click to expand...

+1 to this and the other comments above re chassis protection.

I have never even noticed if my levelling knob has a light or not. all I do know is that when driving especially in the dark,I,couldn't see it anyway, so I go for it by touch.
But then mine aint a facelift!
When driving in Frogland, I use it to obviate blinding the oncoming traffic, then put it back up on the open road, or on autoroutes.
Now I'll have to go and have a bloody look, won't I?