Fray Bentos wrote:

Why is this ? the flue/chimney is good with air being drawn through and
besides, the outer two bars are ok.

Does it tend to spend most of its lit life with just the inner two
burners on? When this is the case, you often see a difference in the
colour of the centre burners after a while. I presume this is due to
accumulation of combustion deposits on the radiant reflector and grill.

--
Cheers,

John.

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