I picked up a pair of used mp40's and one works awesome the other just I just got around to setting it up today. Its spinning and clicking constantly. The spinning gets much worse with speed and the clicking is always present. I took it apart to make sure nothing in it and it was clean but the propeller spins very tight or hard or has resistance.. not sure how to describe it. Also former sailor so sry for the words, they come out and I don't even notice them till later. Easy fix or did I get shafted?