Hi - suggest you open the hob, unscrew all burners and inspect the connections, electrodes and igniters. I just did that on my SMEG hob and found that the ceramic was cracked on two of them. Just sent an email to SMEG, Italy about it and they are totally uninterested. Anyway, I had purchased a replacement electrode for one of the burners and the other I was able to glue. Now both are lighting but I have a second problem of one of them as the gas stop as soon as I release knob.
ak
July 2021
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