So working on your post, I've stripped the PCB out the head,
Plugged that into the head connection,
that way I can slip my multimeter directly into the PCB sockets, & see what's going on
So switched on, no DC reading from the PCB & while it was on,
seen that little blue spark coming from the PCB,
Attaching a pic, it came from the grey resistor like part, you can see a small black dot on the right, that's where the spark comes from.
So looks like a new PCB it is then,
Many thanks for the replies.
Will post update once the PCB arrives