I have been searching for replacement cam box oil seals,the ones above and below the rockers. I have adjusted the oil feed to the box as the book describes also checked the presure which is good. The cam tube in the box has a small crack on the inlet side at the base of the tube but it is slight. Are new seals available? I have been using straight 50 weight oil and recently changed to castrol R30 a caster oil which has slowed the oil loss