FYI.... The very first pump that I received and put in operation, has always been a little noisy. I had taken it apart before and cleaned it, but it didn't seem to make any difference in the noise level. Over the last week it has become increasingly louder, so I decided to take it apart and see what I could find out. Under closer inspection I noticed that the front bearing didn't appear to be fully seated in the housing, so I firmly pushed it back into the housing, When I restarted it, I didn't think that it was working because I didn't hear anything?! This pump is now the quietest one I have! I plan on taking the other 2 apart tomorrow and inspecting them. Just wanted to pass this on.