Thanks richard

That was or lrparts.ru site only giving me 1 part number.

Lrcat shows all.

Found a used one on eBay with black plug.
Be here next week from Germany all being well

Well thats annoying! Been out today and no problems.
I'm guessing the heat from the engine and gearbox have dried out the switch.
Still going to change it for other one.

Thanks for all the help 😀

Well at least it's fixed itself for now 🤗

Indeed. Wasn't looking forward to 160m drive home in 3rd gear.

Maybe spray water repellent on it and connections 🤔 As you say it's probably water got in it somehow

It'll have got in through the breather on the top. Get a bit of washer pipe, bend it to a U shape and fit it on so the open end is pointing downwards. Then you will be able to drive through fords (and over some of the smaller Fords) without filling it full of water.

I presume you mean windscreen washer pipe?
I'll pull it off when the other one arrives and fit other one after checking the switch works.
Thanks guys

For info, I've just received the switch and now see the vent.
Next to the wires entering the switch.

It seems the breather is supposed to run into the engine bay looking at a new one.