After 12 years, I needed to replace the 1/2 HP Hayward Super II motor for my water feature. Two things happened during the replacement. First, when I went to pull the diffuser off, one of the tabs that holds it on snapped off. That left four tabs, so I did not replace the diffuser. Second, during the disassembly, I somehow lost the gasket that goes between the diffuser and the pump housing. I went to Leslie's to buy a new one, and the guy there said that gasket does more harm than good and he never uses it, so I did not get a replacement. Motor seemed to go together fine, but pump is now putting out less than half of what the old motor did and you can see severe cavitation through the strainer cover, like the pump is pulling half air. No apparent leaks anywhere I can see. Any suggestions?