Quick question, thanks in advance for any help. I am changing the oil for the first time on my newly acquired 02 WR426f. The parts schematic shows a gasket on the crank case drain plug that should be replaced. My plug has a silver washer on it that doesn't come off. Is this the gasket that has been reused so many times its formed on to the plug, or is that part of the plug and there should be a gasket between this and the crank case?