Go to your local auto parts store or Harbor Freight and get a metric selection box of O rings. Changing the O rings each time you change the fuel filter is a good thing. The copper ring goes under the head of the bolt... (Belt and suspenders)

The same goes for any place you have any O rings. Remove and replace the hard old rings with new ones. It's just a good practice.

Pete

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Pete Williams, President emeritus - MBCA-International Stars (Eastern Mich.) Now Wi. & Az.
1985 300D Manual 4 speed Green Hen's tooth
1979 MGB triple black Az car nice
1969 back 1/2 of MGB (Az home built trailer)
1991 Volvo 245 Wagon Nice AZ Restored Gold Brick
1983 Jeep CJ7 37,600 Miles Summer use only