Attwod water heater issue

moving the slider has no effect. It's a super yellow flame, and sometimes flares when lighting like it's pooling up instead of flowing if you know what I mean. there is plenty of airflow available, so I'm thinking gas flow is the issue. I'm about to go out and disconnect the gas line at the tank, and at the water heater, and blow air though it to see if it's somehow plugged up. I might go fill the tank up today to make sure it's not just low, even though the gauge shows 1/2 tank (and I have gas at other appliances). Local shop I usually fill at is closed today, but there's a gas station nearby with a tank that opens at 2p. We'll see if I resolve it before that lol.