I have the same boat and had the same problem. Mine went out. You will have to remove the oil tank to get to them. The motor cartridge comes out the holder and is replaceable. It's a little tuff to change it cause the gas tank sits on top. You can take the gas tank out if it's empty but not necessary. If it's the same as mine you will have the 500 GPH. I would recommend to upgrade to the 700's as this will pump harder and faster. They can be bought at a local dealer.