I have a couple of mag-drive pumps that will not restart reliably. Anyone know the cause of this? I have cleaned them a couple of times but no luck. I think one is a mag-5 and the other is a mag-7. Nothing appears to be wrong with the impeller. It seems that I saw a post ages ago where hole in the impeller cover (the one that the impeller shaft fits into) gets ever so slightly oval'ed out and causes the impeller to bind up on start-up. Not sure if there is any truth to it or not. Is there a cheap fix? Hate to go throwing $150 worth of pumps in the garbage. About the only thing I can rely on them for now is for mixing salt.