I have a hayward super pump II. It is not priming on its own. To get it to prime I must shut all 3 intake valves from my skimmers and the main drain, put water in the basket, turn on the pump and then 1/2 way open the closest skimmer. I must do this 3 times to get the thing to prime. I can not figure this out! I replaced the o ring on the skimmer basket and it primed perfectly for a few days then stopped. I do need a new o ring on the filter and have a slight leak there but I dont think that is the problem. No air coming in the skimmers. No other visible leaks that I can see. Obviously air is getting in there some place. What other gaskets should I check? Any suggestions?