This is a 1989 6 HP 2 stroke. Thought I had a seal leak in lower unit. Did pressure test and the leak appears to be a gasket under the plate that the the impeller housing bolts to. All the bolts are out. Gently tried prying this up and it doesnt seem to want to budge. Don't want to damage it so I need help. Will it eventually pop loose with enough pressure? Is the seal what is holding it in place? Special procedure? Sorry. Still new to outboards. Pic below. Thanks for the help.