Without seeing it, it sounds like water coming out the "weep" hole between the seals. It's so that a leak past one of the seals drips out of the pump rather than being forced past the other seal. Might have gotten one of the seals cocked while replacing the impellar.
I agree. Be careful if the cover plate screws are made of brass. I sheared one of those before and it was a nussance to get everything together again. The hardest part I had was finding a metric screw in stainless.
Between us there was, as I have already said somewhere, the bond of the sea. Besides holding our hearts together through long periods of separation, it had the effect of making us tolerant of each other's yarns -- and even convictions.Heart of Darkness Joseph Conrad
Just check and ensure that the old impeller is the same width as the new one. If the impeller is too long, it may not allow the plate to screw up correctly. Only other thing I can think of is the gasket. You did put the new gasket in I assume??
For God so loved the world..........He didn't send a committee.