I am going to install a new Carb. I recieved the Carb.,and it has a gasket and an o-ring. I know where the gasket goes,but where does the o-ring go? It is a Briggs. Model 122KO2-0577-E1. It is 6.0 H.P. Also self-propelled. [Craftmans] I removed the old Carb. and did not find an o-ring. So any help would be appreciated. Thank You