Not sure what you mean by not moving freely but if you mean the impeller doesn't rotate when inside the motor, there may be some buildup inside the bearing. See post 2 in the link below. Also note that 12 hours in vinegar can damage the pump. Vinegar is used in the boat manufacturing business to clean up cured and uncured epoxy. Epoxy is used in the potting of most pumps and prolonged exposure to vinegar can soften the epoxy and compromise the connection where the wires go into the block as well as the bond for the magnet and damage the rubber o-rings.
I am sending you a PM so we can discuss some potential issues and get clarification of the impeller not spinning freely.
Post 2 in the link below shows the bearings. Post 1 discusses proper cleaning and maintenance which would apply to all Red Dragon pumps.
http://www.reefcentral.com/forums/sh....php?t=2573406
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