[Brad]

Yes, if the gasket is torn your primer will not work properly. When you replace the gasket make sure you take all the residue from the old one off. Plus, it does appear that there is a gasket between the carb and the engine block.

In the meantime, you may need to push the primer a few more times until you can hear/feel fuel being pushed into the carb throat.

 

[Brad]

I just took another look at the diagram. Mark is right, O-ring only. I would not put the gasket on there, but can't think it would hurt anything.