Evening all. Recently purchased my second cb750k, an unfinished project. Just going through the pd41a carbs and am curious about the ball/spring set up that appears to live in the base of the accelerator pump and from what I can make out, one in the no.2 carb bowl. I believe their purpose is to be a type of non return valve for the fuel. My main question is, where the valve sits in the bowl I have a rubber solid gasket as opposed to an oring. Was this standard? It seems odd as it effectively blanks the flow between the bowl and the accelerator pump jet that sits directly above. Should it be a normal o ring? Are these important in the function of the carbs? Any info appreciated. Photos attached to try and make some sense of my waffle. 😂