You should just have a "O" ring on the difuser about a 2" ring at the center opening and one about the size you describe on the seal plate or in the pump housing. Ether one at the outer edge. You probally have a bad seal. You will need to remove the impeller and replace this before you put the pump back together. Generally if you pull the wires and take the pump to the poll store they will do this for you for the price of parts and can match your "O" ring's to the pump at the same time. This is always your best bet once you open the pump to get all this done at the same time. Good luck.
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You should just have a "O" ring on the difuser about a 2" ring at the center opening and one about the size you describe on the seal plate or in the pump housing. Ether one at the outer edge. You probally have a bad seal. You will need to remove the impeller and replace this before you put the pump back together. Generally if you pull the wires and take the pump to the poll store they will do this for you for the price of parts and can match your "O" ring's to the pump at the same time. This is always your best bet once you open the pump to get all this done at the same time. Good luck.