My 1986 190D has developed a leak around one of the delivery valve bodies on top of the injector pump. My CD shows there is both an O ring and a copper seal ring under this delivery valve body. Fast Lane lists a seal, but not both the copper and O ring. Which do I need to replace and is this what is listed in the Fast Lane listing. Are there any problems to replacing these except for having the splined wrench and cleanliness. Also, are the splined rings with 30 torx bolts just to keep the delivery valve bodies from loosening under vibration?