I’ve discovered why one of the point blades wasn’t getting any electricity.
Between the closure rails and the point blades there is a small pivot. This allows the point blades to move and, because I’ve connected power to the frog, it carries the current to the point blade.
I cleaned away the clay and paint that I’d applied around it, pressed the contacts firmly back in place and the current to the point blade was restored.
Phew, I was worried that I would have to dig out the point and replace it. I am very pleased that the solution was a simple one.
In future I will be more carefully when I’m ‘splashing about’ with clay and paint!