Ok you would take the covers and grates off the stove top, next remove the screws holding the burners in place, Once all the screws are out slide a putty knife in the gap between the front and the cook top about 3 inches from each end, Push the clips holding the top on. You can then lift the top up to get to the valve.
To change the valve pull the knob out, remove the screws behind the knob.
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