I am intermittently getting air bubbles in my pump basket and my basket isn’t filling up entirely with water. I started checking the strainer cover O-ring and am now concerned that I’m missing an O-ring. My strainer cover has an Oring that is intact and lubed, but that is the only Oring I have. Looking at the replacement parts list, it shows part 4A the strainer cover kit having and Oring and part 5 the strainer cover O ring. Should there be two different Orings? One in the cover assembly and one between the cover and the strainer basket? or is the diagram just calling out the same one twice?