Hi i'm overhauling a 1991 suzuki gs500 motor, and the oil sump is stuck on really strong. The engine is out of the frame, and with all the sump bolts removed, I can pick up the engine with a tool going into the drain plug hole, and the engine will just hang there, glued onto the oil sump pan. I've tried hitting it many times from all angles with a rubber mallet. I've sprayed both liquid wrench and gasket remover spray around the outside edge of the exposed gasket, and into the bolt holes, but it doesn't seem to be doing anything. Anybody ever a problem like this before?