So my switch has had it. Its not the switch itself but the outer threads that the lock ring attaches to is to completely shot.
Part number is 31 73 53 60
I ordered one from Stein Dinse in Germany (I'm in the UK) and got an SD that's now in the bike but its a piece of junk which I have no faith in, except that it will, one day, leave me stranded somewhere. Its plastic feels shoddy the key has to wiggled to get it in etc: The terminals even collapsed into the switch when putting on the spades, which meant disassembling, fixing that problem then reassembling.
So I've been looking at trying to get something that's a bit better. I've seen reviews of the Zadi which vary from Ok to "another piece of junk"
I just wondered if anybody had found a better alternative, its a 3 position (although a 2 would be fine) 4 terminal job and the my switch does not carry much current as I'm using an M-Unit.
John