It is usually the magnetron that is faulty either down to earth or the magnet is cracked ,either way Whirlpool advise to change the magnetron and board as a pair
Don, those codes don’t relate to this particular model, I found those and they seem to be for US microwaves and smart gas cookers.
The magnetron looks and reads fine and no cracks.
Guess I’ll bite the bullet and go for the board 1st and see what happens but I would be interested to know what F05 does actually mean as I can’t find anything specific anywhere 😕