On the valve cover, make sure the mating surface is not bent out of shape. Use a small hammer, a
piece of wood mated to the cover lip size and a flat surface to tap the valve cover back in alignment.On the slipping gasket,try spraying a little gasket tack on the oil pan lip after it has been properly cleaned with lacquer thinner.
Personally,I don't think using double gaskets is a good idea and remember not to overtighten the
screws/bolts.
