I have a 1979 55HP evinrude. I am trying to replace the water pump but cannot get the foot off. I can only see five bolts, two on each side and one right behind the propellar. I removed them but the foot would not slide out. I have tried twisting, hitting with a rubber mallet, but it will not come out. Is there something I don't see? I don't want to break off the flange around the foot. HELP!