It's now about five years old, and because the switch is buried behind the front sprocket cover, it was completely gunked up with old chain lube, so it needed cleaning before I could even see the old switch. Cleaning the area was a proper pain.
I tried Guy Martin's proper job cleaner- didn't touch it.
Next, Gunk - the original formula ( the green version doesn't work) and that helped, but only to transfer slightly softened old chain lube onto my hands and a chain cleaning brush.
So I got the pressure washer out (yes, I do own one, but I rarely use it).
That shifted the globs of softened grease onto the patio, patio furniture and any plants within three metres, and, of course, my clothes.
So out came an old paint brush, which stirred the slurry around a bit but didn't remove any.
After which I poked an old tee shirt into the remaining gloop and removed as much as possible before fitting the switch.
Perhaps I'll look into one of those sealed for life BMW chains....
At least I'll look like a proper biker at Brands tomorrow, as I have "workshop hands" once again.
I foolishly thought that buying a modern bike would mean less time in the garage and more time riding
