Not sure if you are still looking for an answer but let me tell you we have been using baldor 5hp pumps for a commercial pool, three months ago we purchased a new one. In the last 45 days we had problems with the pump first it made a huge grinding sound then it stopped working we took it back and it was the impeller it had disintegrated, the manufacturer replaced it at no cost except transportation and pool chemicals/labor to correct the pool after it had sit stagnant for 6 days. Last week we started experience issues with the pump overheating and tripping the breaker, we called the installer at D and E pumps, titusville, Fl, they sent a person out to confirm the pump was pulling 35 amps and no matter what we did with the flow it didn't change the amps. We nursed the motor though the weekend and then yesterday the pump tech showed again when the took the pump apart the second impeller in less that two weeks had disintegrated again, the manufacturer is blaming it on the pool chemicals? That is no even possible for muriatic acid to eat a brass? impeller in 2 weeks means that any bather who was in there would have been burned, our water is tested daily and has been in the range of 74. to 7.6. My conclusion is that there is another alloy that is being used/mixed with the brass to lower costs and it does not stand up to pool chemicals. I took the tech to show him 10 years of used impellers that spent 2 to 3 years on the pump, including the last one that was good for 3 years and none of them showed the wear that was present with theirs as a matter of fact they wanted to put an old one on instead of using another one of theirs. Bottom line it is being sent back to the manufacturer but if you have impeller issues with a baldor pump or issues as you describe my bet is the impeller.