Ok, skimmer pump not working. The pump should be a little under four years old.

The guy who got the skimmer that was originally on my tank before I bought it, has had it running for the last six months. I bought it to come back to its rightful tank

it. He took it out of his sump and gave it to me. I know it was running. Its been out of water about two weeks.

It wont work. I hear no hum or anything like its trying to start. Is it dead? He said that sometimes it didnt start back up and to turn the impeller. Well, I took it all apart and have turned it. Nothing happens. Any suggestions? Is four years about the life of one of these? Shouldn't I hear a hum or something if its dirty and needs to be cleaned?