Last Wednesday, I got a temp alarm on our way out for evening races. I looked off the stern, and saw no water pumping. Shut down, and went below to check. Pump would spin, but no water. Luckily I keep a spare pump with fresh impeller in the parts box. I quickly changed out the pump, (just two 1/2" bolts) and was able to make it to the race start on time. This morning, I took the dead pump home and opened it . Impeller was torn and all bunched up on one side. I was able to pry it out. But the central collar seems to be seized to the shaft. How can I remove this with out messing up the shaft or the bearing in the pump? Prying and needle nose pliers have not worked.