Hi, I've got a 351 engine with a possible valve cover leak. I say possible because the lower side of the passenger cover appears to have collected some dust from oil seepage, but not the complete length of the cover, just the front half. This would be the original gasket, can the cover be tightened to stop the leak or does it have to be replaced? There is no spot on the floor so the leak is not a major issue. If a replacement is done do we have a Youtube or other source for reference on the job?