Need some advice. I had a leak on the housing and recently replaced a couple of seals and put the pump housing back together. Previously, the electric motor ran fine. Now when turn my motor on, it hums and then shut off (motor trips off, not breaker). I kept turning it on and off, it actually started and ran. But, when I turn it off, it reverts back to hum and stop. Any suggestions? Main seal? Impeller?