These kind of grills usually have a safety device which controls the flow of gas from the cilinders, as you see to have a problem on both sides I would suggest this is the common demominator, however if and where you can get one, let alone how easy it would be to fit is another issue. I would suggest before lobbing it in the bin though you might want to strip the center unit down and see if anything mechanical is at fault, could be that some debris from cooked food has slipped down inside causing a blockage. !!!Make sure fo course you remove the gas cans first!!!
Stewart, November 2006