Steve, I haven't had any problems with restart yet (knock on wood). I used a Mag 5 before the 7, and I had to keep replacing the impellers on the 5 because they kept breaking for some reason (blades would shatter). The first time it was because the "safety" strainer (the one used to hold the sponge in place) broke and a piece got sucked into the pump. I don't know what caused the impeller damage the second time I had to replace it. Now I keep a spare pump.