Yes there is a glass lid that covers the burners when not in use
I've looked at the mechanism the glass lid operates, it slides an operating lever/arm across the front of the cooker behind the knobs, this looks to be working correctly
are you sure there is a valve, I have looked from the gas supply pipe quick disconnect, then it goes straight into the cooker via a threaded connection. the pipe then goes to the front of the cooker (control knobs)
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