I've got a Cannon Camberley gas cooker and cannot get the electrode to
spark in the grill . The bottom oven and ring burners are perfect,
spark every time. I have tried cleaning existing electrode with a nylon
brush and inspected for loose cables. It sparks intermittently, about
once every 30 clicks. I have noticed that the grill electrode works
fine when the top oven is started, weird!

I have changed the electrode with a new original part, and has not
cured the problem.