I bought this pump as a used item. I only use to do waterchanges and it was working flawless until today. Issue is that the impeller sometimes will spin and sometimes will not when I plug the cord in. When it's spin it's working great and new stop. I took it apart to inspect and notice the impellar shaft was worn out. This would cause the imepller magnet to wear out cuz of spinning unbalance. Do you things think I should get a new impeller shaft and impeller for this Sedra ksp 9000 pump or should I buy a brand new Rio pump for the same price of the replacement parts.