Well it’s working but why.
Decided to have another look this afternoon. Tried it & still not working. Checked fuse continuity OK. (Again) Replaced fuse still not working so removed fuse & went to check voltage. (again) Now all laugh! set the analog voltmeter to 50mva DC rather than 50 volts DC. I use an analog meter. Yes not looking at what I was doing trying to hurry as I was supposed to be cooking super. At 1st touch meter went hard over. Tried again hard over then nothing. Meter fuse gone I guess when I realised my mistake. Much muttering so replaced fuse & replaced cover & closed bonnet. Thought I’d try the button one last time. B’dy it was working. Having switched the oven on for super, replaced fuse in meter. & cooked super.
Did you see that film gremlins, well they/ it is alive and well in my place.