My six burner Thermador gas cooktop PCS366 is having the following problems.

when I use either of the XLO (left hand burners) all the burners will spark and continue to spark after the XLO burner lights. (In addition, there is a slight humming sound when the rear XLO burner is lit - this doesn't seem to interfere with operation but I just wanted to note it)

When I turn on any of the other burners only that burner will spark and stop as soon as the gas is lit - so it is only when I turn on either XLO burner that I get continuous sparking of all burners.
In addition I have one burner (front middle) that will not spark when it is turned on but gas will flow anyway (I can light it with a match) and this burner will spark when the XLO burner is turned on, and if I turn on one of the XLO burners when the gas is flowing to this burner it will light.

I hope the explanation of the problem is clear
Thank you for any advice and help