I requested a new impellor for my 6055 as the old one would click, you sent me one of new revised ones. Here is the problem, I notice that the pump was off tonight, so I pocked around a bit and found the power supply was blinking. I thought great the pump is dead. Come to find out the new impellor was seized on the shaft. I carefully removed the impellor, it was really stuck on there and I replaced it with my old one. It seems to be fine now.