Sure, that's easy. They are fixed jets, not adjustable. If you are trying to adjust those screws, they are not adjustment screws, they are plugs with a gasket under the heads. They are to be tightened down against the gasket.
Sure, that's easy. They are fixed jets, not adjustable. If you are trying to adjust those screws, they are not adjustment screws, they are plugs with a gasket under the heads. They are to be tightened down against the gasket.